Difficult starting and inconsistent idel

[Roni92]

Hi,
this is 45cc dual ring POS rovan engine, it was difficult to start from the beggining, but now its even worse, usually need to lean out low half to one turn to start then get back to normal setting.
But thats one of smallest problems with it, recently it got no power, but not like bogging or anything it will reach max speed, but pretty slowly, engine have no torque at all, and idle behaves strangely: after driving the idle is unusually high, then after idling like this for about 10-20 seconds is getting lower to normal rpms.
I know its not mixture needles issue because was tinkering with them a lot and it doesn't help at all. Spark plug looks almost perfect (light brown with small amount of deposits).
I also don't have seal on the header-exhaust connection, because they are all melting almost immediately... I know not sealed exhaust might be part of the problem, but the thing is last time I was in gravel pit with this setup she run fine, at least as fine as you can expect from that pos engine, but at least it worked normally and accelerated decently.
I head idle issues can be cause by not tight intake, so I dissasembled it today but everything looked normal, I mean seal next to two screws was broken but only around screws, not where the actual air comes through.
I oiled them today with filter oil to help with sealing, and made sure pressure impulse opening thingy is clear and seal is not blocking it but it was fine anyway.
Also made sure that fuel lines are connected to proper spots in carb - the black one with filter goes into bottom and clear(yellow) is connected to upper thing, so ithinkg its proper.
Also this engine generates enormous amounts of heat, and head regularly run at 180*C but i heard this is how it is with those pos engines.
By some miracle it still hasnt seized in about 8 tanks of constant issues problem solving and overheating
Every time i go out with it im wondering if it will finally kill itself (and I think I subconsciously want that ).... hate it with passion.
After about 20-30mins of driving it loses almost all power and dies without throttle and will not start again the same day. At that point everything under body is so fuc**ng hot you can almost burn yourself even on chassis...., even plastics have 100*c.......(its why i don't want to put lipo in it, it will f***** explode from heat) Its like this every time. I think this engine have like 5% or less efficiency, all burned fuel is wasted into heat .
Its really strange because my bajas 29cc is the exact opposite, works perfectly with no issues from the begiining, vehy good power for the price, and always starts effortless with one pull, just loud as mofo.

 

[spents]

the 45's are known for running hot dude,
i have a single ring 45 and i got a good one tbh, the twin ring ones run hotter than the single ring as well,
you have an air leak by the sounds of it, i'd start with the carb insulator block cos some of the rovan ones are really bad,
the insulator cracks between the pulse hole and the intake hole, or some of em crack all the way across,
rovan made a load of em with really bad mix of plastics and the bad ones just look bad on the finish,
so get yerself some fresh gaskets and a new insulator block and try that first,
also if you overheated the engine the insulator will be warped and will never seal proper again unless you flat it off on each side,
as you've run in a gravel pit i'd also suggest having a look at the piston and bore to check for any bad scratches etc, you can have a quick look through the inlet and exhaust ports, but easiest and better to pull the head off, if the piston or bore is badly scored then get a fresh top end kit, they aint expensive,

 

[Seandonato73]

the 45's are known for running hot dude,
i have a single ring 45 and i got a good one tbh, the twin ring ones run hotter than the single ring as well,
you have an air leak by the sounds of it, i'd start with the carb insulator block cos some of the rovan ones are really bad,
the insulator cracks between the pulse hole and the intake hole, or some of em crack all the way across,
rovan made a load of em with really bad mix of plastics and the bad ones just look bad on the finish,
so get yerself some fresh gaskets and a new insulator block and try that first,
also if you overheated the engine the insulator will be warped and will never seal proper again unless you flat it off on each side,
as you've run in a gravel pit i'd also suggest having a look at the piston and bore to check for any bad scratches etc, you can have a quick look through the inlet and exhaust ports, but easiest and better to pull the head off, if the piston or bore is badly scored then get a fresh top end kit, they aint expensive,

Yep hit that one right on..... time for a pressure and vac test.

 

[Roni92]

tl dr;
scored piston, scored cylinder, warped insulator block, bad intake leaks, "engine" not worth repairs, just get zenoah or obr.
Some for future generations/mini review summary:
Despite total pos engine car is still decent deal/value, very good shocks and drivetrain, good chassis and electronics, reasonable well put together from the factory, good stock setup.

yes so my saga continues, i only today read replies, and yes everything spents said checks out. I had warped intake manifold. I bought high temp silicone especially to fix it since i couldn't find any of those manifolds other than China, did 2 attempts with it, air leaks sympots MOSTLY went away - revs were still slow to go down to idle and onlny richening low helped it - maybe its normal behaviour when your low is too lean to slowly drop rpms to idle? - i don't know, i don't havy any of those problems with baja and info about such details on webs is very sparse so cant say.

Yes i have badly scored piston and cylinder from the looks of it, but honestly i don't give a *** about it anymore, im buying zenoah nexgt month when new budget allows it..... im so pissed seriously, i had this car for month or two, burned like 5 tanks already but not a SINGLE normal driving session,
i taken out engine from chassis more times than driven it, im not kidding; im through with it, imo buying anything for this engine is complete waste of money, it have no revs, no torque, nothing. Im absolutely 100% sure that 29CC from baja have way more torque and power than this pos.. and yes i know baja is 50% lighter.

Anyway so some time ago i bought ddm clutch bell and 23T pinion(because there are no other pinions for stock hex mounting bell) and the idea was to compensate low rpms of that engine with high gearing, as everyone on nets is saying "its a torque engine". But its not. Now its still slow, but acceleration is super bad and a lot of clutch slipping, it just doesn't have the power to pull it.
It would work fine if those statements about over 4hp were even half true. I wasnt against this engine despite everyone said its low revving because i know its about power, not rpms. If you got x power, you can get it moving, its just matter of gearing. But like i said even that doesn't help it, actually makes it even worse.

I was aware those engines arent good and had plan to get proper engine like obr or something anyway, but I thought i could at least have month or two of SOME fun with stock one to get at least some value out of it. But unfortunately not, it was all frustration. Every. Single Time.
Despite having so much frustration i still believe i made better deal than buyuing losi. Even if you take that pos 45cc and throw it into trash and get fresh zenoah 32cc im still at 1300€ total vs 1900€ for losi, and chassis and electronics are solid(and that monster energy body is f**** sweet lol). Its just that f**** engine that spoils everything.

So i found new intake manifold ordered, and will drive it few more times before im able to get zenoah and then i will probably take huge hammer and take this "engine" out once and for all )
Seriously if they were selling those as rollers or just no engine for like 700€ that would be so sweet deal. For 300 bucks ud jsut get zenoah and be set good. But as of right now you have to pay for useless engine. If i only knew whats pos that 45cc is id get 36cc version other shop had, at least it would have some revs.

also to summ it up I believe i haven't done a single thing wrong with all this and had all those issues.
If I set carb too lean or too rich, if i drive without air filter or not oiled filter, sure that would be my fault. By i didnt do any of those things, engine was running super hot from the beginning. Its just faulty unit imo, nothing more nothing less.
Imo this company should return value of that engine but i know its Chinese company and its not worth even attempting any of that but im just saying, thats what any normal company should do when their product is simply useless/doesn't work.

also don't buy ddm or how they called clutch bell. Had whole another saga of adventures because of it...... It was so bad fit with their own pinion i spend 3 hours with dremel to make it fit without locking outer bearing. id get refund if not for the fact that it was shipped from UK so not worth it...
;

rn im waiting for new insulator block and will try one last thing - with carb from baja beacuse im starting to strongly suspect faulty carb after last drive with fixed leak - it ran fine for 5 mins and started to go into moods again. Also i got very lean at the end and i notices that fuel pump buld got empty - what that can be? I read that it can be because of heat, but it was like 5 minutes of running, carb wasnt hot. AFter taking taking intake AGAIN pulse opening wasn't blocked - so again, dunno.
If baja carb or new intake manifold fix it ill keep driving it until zenoah comes, if not ill throw it into corner and drive baja until then.

to finish this with at least something positive - through all those issues and frustration at least i learned a lot a bout those 2 strokes and can take it out from chassis with closed eyes

 

[spents]

i think you just got a bad one unfortunately mate,
its always hit or miss with rovan engines , but seems you had really bad luck,
the empty bulb is probably heatsoak from the engine, like you say its always run very hot,
do the quick fixes and run it till it blows, then get yer obr/esp, or stock zenoah and move on from there

 

[Seandonato73]

i think you just got a bad one unfortunately mate,
its always hit or miss with rovan engines , but seems you had really bad luck,
the empty bulb is probably heatsoak from the engine, like you say its always run very hot,
do the quick fixes and run it till it blows, then get yer obr/esp, or stock zenoah and move on from there

Known warped insulator... weak pulse signal to carb....

 

[spents]

Known warped insulator... weak pulse signal to carb....

yeh now ya said it sean

 

[Roni92]

i think you just got a bad one unfortunately mate,
its always hit or miss with rovan engines , but seems you had really bad luck,
the empty bulb is probably heatsoak from the engine, like you say its always run very hot,
do the quick fixes and run it till it blows, then get yer obr/esp, or stock zenoah and move on from there

Thanks, thats the plan.
New insulator came today, tried to mount it and metal thread insert got ripped out from plastic. I have no words...
Does anybody know if zenoah comes with insulator block? cant find any info what comes with engine exactly

 

[KevTrem]

With a G320 in these trucks you will be able to run a 20-21tooth pinion without issue. I went from the 30Degrees north 29cc engine (which was miles better than the KM30.5 I had in my Baja) to a stock G320, using the 30DN exhaust. It's much, much better, and it wasn't bad before on the 29cc just wanted more power.
You'll find the G320 starts very easily and runs well, remember to order a throttle linkage as chances are the one for the 45cc wont work on the G320, a stock linkage for 30DNT or Losi5 will work just fine.

Keep at it fella, you'll get there.

 

[Bandit2013]

The Zenoah has a composite insulator block. Thought about changing it but what I took off of the Rovan 36cc engine did not fit. I bought the Zenoah-ESP G340RC standard port engine. No issues with the Zenoah after many tanks of fuel. I replaced it with a Taylor 35CC engine on the one Baja and finally got around to disposal of the Rovan 36 engine on the other Baja (this is where the Zenoah-ESP has found a new home).

As for the Rovan/ROFUN = NOFUIN 36cc engine, they would run a few more tanks than the 45cc but same issues. No RPM, no torque, lack of any power and likes to overheat, sounds like the NOFUN 45 engine but has better cooling (assumed). Already melted the cylinder head cover. I have two of the NOFUN 36cc engines. One I bought in place of the KM30.5 engine and the other is a stock engine on the Rovan Baja 360B. Will have to pull off all of the good parts and tear it down like I did the other NOFUN engine.

The smaller King Motor 30.5cc engine was way better, however the Zenoah-ESP stroker is hard to compare as I have not fully broken it in yet. Keeps getting better the more I run it.

Sorry to hear of your NOFUN woes. I can understand wanting to get at least something out of the engine before you need to upgrade. Check the screws on your differentials as I have seen many videos on those being the common issues with the LT.

 

[Roni92]

You'll find the G320 starts very easily and runs well, remember to order a throttle linkage as chances are the one for the 45cc wont work on the G320, a stock linkage for 30DNT or Losi5 will work just fine.

Keep at it fella, you'll get there.

Sorry to hear of your NOFUN woes. I can understand wanting to get at least something out of the engine before you need to upgrade. Check the screws on your differentials as I have seen many videos on those being the common issues with the LT.

Thanks for feedback and kind words mates it helps
-If you got 30dnt im so jealous. Tried to get it from UK for few months but thats another story. Thats why im stuck with this turd, it was second best option.
Not sure why throttle linkage wouldnt work? Unless carb is in different spot? Ill have to look that up, thanks for heads up.

-NOFUN haha i like that i have to start using that Regarding screws actually im not worried about, both my NOFUNS were put together surprisingly well with threadlocker in all proper places, actually had to torch heat up center diff to get inside it. Got few loose screws in baja after some time, one shock end on LT but thats it in terms of screw issues. Now im armed with blue and red loctite so im not screwing around anymore and add it profusely everywhere as i found if you try to add small amount for less force it wont do anythinig, it needs certain amount to be effective.

Anyway more disasters from NOFUN: just tried carb from LT on my baja to make sure carb is fine(that imo eliminates most of potential other issues as baja works perfectly and no intake leaks etc). Fun fact, both carbs looks almost the same but one from LT have "original" walbro markings and even "japan" on it while bajas one have "ROFUN" on the bottom of it. Im pretty sure its same s**t from same chinese factory.
Anyway I digress, so i put this "WALBRO" carb on baja engine, set factory needle settings, pump some with bulb, do few slow pulls and start yanking.
I jerk with no throttle, with full throttle and nothing. Not even cough. Maybe its on choke? Nope. Maybe I flood it? Nope, spark plug dry.
Try to lean it out as its the most sure way to start in my experience. Nothing. More rich? Nope. Behaves like it doesn't suck in fuel at all, at least thats my suspicion.
Ok so mabe I screwed up something when dismantling and putting together intake and all that jazz?
After few tens of really hard pulls i give up and mounting stock baja carb back on it, same procedure, stock settings, few slow pulls, 2 fast pulls and starts right away and idles perfectly like its Japanese engine.
Conclusion? Carb prolly also f****ed?
I was so hoping i could reuse that carb for G320...
cuz i could order G320 without carb for 250€ and now i have to order with carb for 300 :/
And im no from land of dreams, 50€ isnt nothing for me, in Poland i could lived for week for that
So anyway will I need to get anything more to put and run stock zenoah in LT? I heard clutch housing is different by i guess i can take one from 45cc?

 

[KevTrem]

Thanks for feedback and kind words mates it helps
-If you got 30dnt im so jealous. Tried to get it from UK for few months but thats another story. Thats why im stuck with this turd, it was second best option.
Not sure why throttle linkage wouldnt work? Unless carb is in different spot? Ill have to look that up, thanks for heads up.

-NOFUN haha i like that i have to start using that Regarding screws actually im not worried about, both my NOFUNS were put together surprisingly well with threadlocker in all proper places, actually had to torch heat up center diff to get inside it. Got few loose screws in baja after some time, one shock end on LT but thats it in terms of screw issues. Now im armed with blue and red loctite so im not screwing around anymore and add it profusely everywhere as i found if you try to add small amount for less force it wont do anythinig, it needs certain amount to be effective.

Anyway more disasters from NOFUN: just tried carb from LT on my baja to make sure carb is fine(that imo eliminates most of potential other issues as baja works perfectly and no intake leaks etc). Fun fact, both carbs looks almost the same but one from LT have "original" walbro markings and even "japan" on it while bajas one have "ROFUN" on the bottom of it. Im pretty sure its same s**t from same chinese factory.
Anyway I digress, so i put this "WALBRO" carb on baja engine, set factory needle settings, pump some with bulb, do few slow pulls and start yanking.
I jerk with no throttle, with full throttle and nothing. Not even cough. Maybe its on choke? Nope. Maybe I flood it? Nope, spark plug dry.
Try to lean it out as its the most sure way to start in my experience. Nothing. More rich? Nope. Behaves like it doesn't suck in fuel at all, at least thats my suspicion.
Ok so mabe I screwed up something when dismantling and putting together intake and all that jazz?
After few tens of really hard pulls i give up and mounting stock baja carb back on it, same procedure, stock settings, few slow pulls, 2 fast pulls and starts right away and idles perfectly like its Japanese engine.
Conclusion? Carb prolly also f****ed?
I was so hoping i could reuse that carb for G320...
cuz i could order G320 without carb for 250€ and now i have to order with carb for 300 :/
And im no from land of dreams, 50€ isnt nothing for me, in Poland i could lived for week for that
So anyway will I need to get anything more to put and run stock zenoah in LT? I heard clutch housing is different by i guess i can take one from 45cc?

Clutch housing is different and so is the fan cover. Depending on where you buy the G320 from you can spec it for Losi fitment usually at no extra cost.

 

[Roni92]

I cant spec it at that shop. I can buy with or without carb. With that in mind, u know if i can move over clutch housing and fan cover from 45cc? or will i need to order that

 

[Seandonato73]

No you will need g320 specific parts.

 

[Roni92]

Roger, thanks.
Anybody knows why 29cc didnt even cough on carb from 45cc? Or what may be wrong with that carb? It behaves like it doesn't want to deliver fuel very much, even on 45(but on that it eventually starts). I know more or less how that stuff works but im green with carbs, never disassembled one, pulse opening isnt blocked, but can i with standard tools get to that pulse pump thing to see if its ok? and what can be wrong with it and how can i diagnose that. Still wanna try and fix that carb before ordering new with zenoah. Thanks

 

[Bandit2013]

It could be the spring on the pressure port valve is too strong. I believe there was a thread on that subject here somewhere. Pop-off pressure. This is where I saw it first. As it seems, most of the small carbs have incorrect spring used on the valve which results in lean operation due to increase in pressure to compress the spring to allow fuel flow into the jets. You could cut a few loops off of the spring and see if that helps. I would also look replacement spring of the proper tension (they are hard to find though since most are aware of the fix and buy them up). https://www.largescaleforums.com/threads/carb-issues.28016/#post-351001

 

[Roni92]

that was surprisingly easy mod to do lol thanks for info. it did something but its still all over the place, im giving up on this engine and carb, its not worth all the nerves, so no more bothering from me in this thread

 

[Seandonato73]

Yep, clip coils instead of getting a different spring. Just like an amateur. The pressure port is called the inlet needle. There is pop and reset pressures. Cutting coils lowers pop pressure but increases reset pressure.

 

[Roni92]

Zenoah finally came today
Mounted all chassis-specific hardware and new sintered clutch asap(cool thing but dunno why they call it sintered, its just clutch like any other just without clutch pads, its all metal, 6k spring), protectors for engine fan intakes from pantyhose, remote killswitch.
Visually its nothing special, but when you pull pullstart you can feel how tight and precise piston moves in that cylinder, crazy compression.

Put some wd40 into cylider to give her some lubrication before first pulls. She started pretty easily, did about 10-15 slow pulls then about 5 quick and off she goes.

Damn im so glad i didnt cheaped out and got it with ori walbro 1107, at least now i can be sure everything is new, sealed and will work properly.

Started doing heat cycles, after fourth started slowly driving. I read that clutch also need break in so its cool that i could break it in simulatnously with engine. Engine temps are superb, 70-90 when idling depending on exact spot. Thats crazy to compared to nofun 45cc which would overheat from literally idling and was going into 100+ at idle in like 30seconds from start . So finally no seventh hell under the body, yay!

After about 6th heat cycle I allowed rpms to go up with about 30-40% throttle. Indeed speed is pretty good rn with 23/58, i mean nothing impressive but id say acceptable, about 55-60 visually - not measured, but i been driving my electrics setup for about 65-70 for years so have pretty good feel for what is about 60.
but power in general? not impressed honestly. Maybe i expected too much from all the hype i read about this engine?
Certainly it lacks torque with that gearing, 21t pinion is max for decent acceleration. But for type of terrain im driving - lot of open space, ill stay with 23t, and since ive got all metal clutch im not worries anymore about wearing it, so im fine with some more clutch slip; will end up with 2 speed probably, but thats just plans.
Oh well its not like i regret buying it, at least now i have normal, working engine and can finally start driving my LT normally.
Its just too heavy pig it seems for all those lower priced engines. You really need those 1000+€ taylor engines to wake this pig up.
Thats absolutely not for me though, i spent on it already way more than i wanted

Now i will just enjoy working 5ive clone with decent, reliable engine.
In the end i still enjoy my pos 440€ pretty much stock baja, thats still quicker and more fun than LT with zenoah engine haha.
It just confirms that more expensive doesn't equal more fun Id be really pissed if Id bough original losi though, cuz thats just crazy cash for such a slow and heavy pig...

btw i wasnt driving on that stock walbro intake, replaced it with my proper one after second heat cycle
link to photos
https://photos.app.goo.gl/E6Hg8dJ9UaXvBWM26
last photos shows plug after first and second heat cycle,
internal piston and cyl before first start for future reference
enjoy

 

[Bandit2013]

Give the engine some time to break in as it should improve with use. When I swapped over to the Zenoah-ESP G340RC (Stock port) engine in a Baja I was not immediately impressed either. It was better than the RovanRofun 36cc engine but yet seemed a bit slow at first. I did not bother to run more than a 5 minute heat soak and just ran the vehicle on the ground (this was recommended by the manufacturer to start with). The Zenoah will wake up after a few runs as it does take time to seat the ring. After that point it just got better every run with the Zen.

• If the LT does not improve performance wise, I would consider some gear changes to see what will improve acceleration. Due to weight of vehicle, consider torque over top speed. This will also aid in reaching the upper RPM range of the engine.
• I would also consider change in air filter intake set up. The stock Zenoah part will not breathe as well as some aftermarket parts. I generally use the ram air filter with a velocity stack on my Bajas (Zenoah and Taylor 35). I am sure the Losi guys can recommend what to go with. The least amount of air flow restrictions the better, sure you still need a good filter to go with it.
• Exhaust is the other factor too. Depends on how loud you can tolerate. The Taylor exhaust for the Zenoah/34+ works great. I used a similar one on the Kraken KV5TT when I started out (it is different than the Losi 5T due to its shape but should perform.) Again, the Losi guys can recommend what works best with the Zenoah on the LT platform. Not sure if it is more related to the 1.0 version or the 2.0 version of the 5T.