Rovan 36cc engine issue

[davehour]

Well it’s pretty much a complete engine minus coil..flywheel..carb and intake..ETC

So everything else needed to complete the engine is taken from the Rovan 36cc?

Thanks.

 

[Bandit2013]

Thanks for the comments on the Zenoah move. Still have mind set on the Taylor RC 35cc one of these days. Not yet certain if it will end up in the Baja new build, or something else; a Losi 5IVE-T, Vekta KV5TT roller kit, or an outlaw hybrid build. For now, the Zenoah 34 stroker (non-ported) will be a starting point, that will end up in the Baja new Build I did recently.

Still have not gone into details as to what is going on with the Rovan 36cc issue. I believe the issue is blowby around the sparkplug and not the casting. What snapped was the compression ring /dual washer on the spark plug or at least that is what it appears to be for the moment. Threads in the head look good. I did try another spark plug but that also resulted in pooling fuel around the plug but did look like it was seeping through the casting seam. I will get it fired up again now that the cover is off.

Soapy water or bake cleaner? Or is there another method? I may have the carb running rich as I was trying to get more out of it on top end, engine never got to that drowning sound, seemed more like it was running lean. Air leak around carb is possible, could be the throttle shaft as I can see there are signs of leaking there as well. You get what you pay for. This engine came on the car to start with. It was intended to be a shelf queen of sorts. What is the purpose of that? The only thing I would buy that sits on a shelf would be a clay tempered (shinken) Katana made of T10 tool steel. It costs as much as a Losi 5IVE-T and if misused it will cut your leg off. Was also thinking of a Katana + Wakizashi Daisho set. The wakizashi is a little shorter so it would be easier to use on home intruders. the Katana would be better outside when arguments with the neighbors about my gas-powered hobby (not being serious on that subject matter, just a poetical expression only.) Another bucket list thing I suppose. To me that would be a shelf queen, it is real and will work as intended but best left on a shelf for display purposes only. Sure, I could get an ornamental thing as it would be less expensive. However, if it is not the real deal, not worth buying it. Shinken means real sword and not some ornamental sword. Yeah, this is off topic to some extent.

 

[DonnieD]

So everything else needed to complete the engine is taken from the Rovan 36cc?

Thanks.

Yep in fact that’s exactly what I did with the exception of the DDM billet intake that comes with the nylon gaskets…hate the POS intake CY uses but there are 2 little things for the kit you’ll need which is wrist pin clips and wrist pin I think…anyway read the description before you order to make sure…I can’t afford those $1500-$2300 engines so if your on a budget this is the best bang for that hard earned buck..IMO

 

[Bandit2013]

So everything else needed to complete the engine is taken from the Rovan 36cc?

Thanks.

I will be replacing the entire engine including the carb and air filter assembly. Not sure about the pull start. If it is not as crappy as the one I had on the KM30.5 I will change it. How much of a clone is the Rovan 36cc engine? Did it really come with a Walbro carb? Rovan claims the Walbro 1191`is the same as the WT-1107. I assume the flywheel and fan cover would fit with a rebuild kit. However, there is that chance nothing will fit when reusing parts from the 36cc. I went for a complete engine from DDM.

https://www.davesmotors.com/ESP-Modified-Zenoah-G40RC-Engine-Complete-HPI-Baja-Losi-5ive-DBXL?sc=12

Will figure out what to do with the Rovan 36cc in question in my case.

 

[DonnieD]

I will be replacing the entire engine including the carb and air filter assembly. Not sure about the pull start. If it is not as crappy as the one I had on the KM30.5 I will change it. How much of a clone is the Rovan 36cc engine? Did it really come with a Walbro carb? Rovan claims the Walbro 1191`is the same as the WT-1107. I assume the flywheel and fan cover would fit with a rebuild kit. However, there is that chance nothing will fit when reusing parts from the 36cc. I went for a complete engine from DDM.

https://www.davesmotors.com/ESP-Modified-Zenoah-G40RC-Engine-Complete-HPI-Baja-Losi-5ive-DBXL?sc=12

Will figure out what to do with the Rovan 36cc in question in my case.

Well CY engines are just very low quality and the carbs are a clone of walbro from what I’ve been told but how I’ve been doing it is run what ya brung til your tired of f$$king with it and upgrade…I never thought there could be such a difference between CY and zennies but you just can’t beat the Japanese when it comes to 2 strokes hell any small engine and they run great…funny iVe got 2 36’s sitting in a box and one only has like 2-3 hrs of run time…just keep them around in case but Think im gonna build a shitshow basher for my buddys to beat…lol

Well CY engines are just very low quality and the carbs are a clone of walbro from what I’ve been told but how I’ve been doing it is run what ya brung til your tired of f$$king with it and upgrade…I never thought there could be such a difference between CY and zennies but you just can’t beat the Japanese when it comes to 2 strokes hell any small engine and they run great…funny iVe got 2 36’s sitting in a box and one only has like 2-3 hrs of run time…just keep them around in case but Think im gonna build a shitshow basher for my buddys to beat…lol

Here a video of that engine in my Losi I took today in the snow…she starts bogging a bit with the extra ten lbs of snow in the chassis and a soggy air filter

 

[Bandit2013]

Well CY engines are just very low quality and the carbs are a clone of walbro from what I’ve been told but how I’ve been doing it is run what ya brung til your tired of f$$king with it and upgrade…I never thought there could be such a difference between CY and zennies but you just can’t beat the Japanese when it comes to 2 strokes hell any small engine and they run great…funny iVe got 2 36’s sitting in a box and one only has like 2-3 hrs of run time…just keep them around in case but Think im gonna build a shitshow basher for my buddys to beat…lol

Here a video of that engine in my Losi I took today in the snow…she starts bogging a bit with the extra ten lbs of snow in the chassis and a soggy air filter

You need some of these to get through the snow. Only kidding. Think they are more novelty. Since you have 4WD, you need two sets.
https://www.rovanrc.com/product-rv85195o
Odd, it turns out the spark plug was cracked. I could not get the fuel leak issue today with new plug installed.

That would explain why there was no resistance after the engine was at temp when I tried to restart it. When it crapped out, sounded like the engine was starving for fuel. Tank was practically full. Fired up the next day. Also, I had this plug in the engine when I noticed the fuel pooling around the spark plug hole. Today, plug was toast and could not get the engine to run. Replaced the plug from another engine and it fired up, no issues of exhaust or fuel bypass around the plug or leakage at the casting seam. Will have to get the engine up to running temp and see if that occurs again. If not, I will end up with a spare 36cc. I will run the engine until it is dead and rethink my strategy moving forward.

As for the Zen, that one will be installed on the Baja that was built with the rear end mostly RCMAX/Taylor parts along with some Turtle stuff. A few Rovan/ King Motor parts were used including the chassis, front end, roll cage, bumpers and exhaust.

 

[DonnieD]

Sharp…my Baja and Losi are both full of a mixture of the same lol…and I’m wheel broke…between the Taylor Gennies and BRP’s and not to mention my Kraton just eats tires…and I’ve gotta get some super spikes cuz the knobbies ain’t cutting it so ya lol

 

[davehour]

Yep in fact that’s exactly what I did with the exception of the DDM billet intake that comes with the nylon gaskets…hate the POS intake CY uses but there are 2 little things for the kit you’ll need which is wrist pin clips and wrist pin I think…anyway read the description before you order to make sure…I can’t afford those $1500-$2300 engines so if your on a budget this is the best bang for that hard earned buck..IMO

I’ll check that out.

In regards to the billet intake manifold, I have read numerous complaints regarding them over the plastic ones. Can you expand about this?

Thank you.

 

[DonnieD]

Well to me a couple reasons…aluminum dissipates heat quicker and that plastic will warp from heat over time and prone to air leaks…if you’ve ever been fortunate enough to own a vehicle with the plastic intake manifold you’d completely understand lol…1990’s ford contour did and went through 3 intakes due to said warp

 

[Bandit2013]

I had a good opportunity to run the Rovan today. 58/16 gears, 7k clutch spring. New spark plug. I was running way on the rich side previously, so I did make some adjustments to the carb yesterday morning. Started at defaults. I did not have to make any adjustments today and the engine ran without issue. No leaks around the spark plug or along the head casting seam. Ran the tank dry (almost). WOT, the rear loses traction. Damn Rovan tires. Thinking on the Duratrax lockups since the viper and others are sold out everywhere. What I have now is just ok but they do much better than the stock treads.

I am not running any screens on this one yet. I did cut away the melted plastic on the cowl. I left as much as possible so there would be no forced air in the direction of the carb. I did not feel like putting the body or rear wing on the car if I needed to remove the engine if what I thought was correct and the head was cracked. Performed well actually.

If the Zenoah with 34cc stroker is more of an engine than the Rovan 36cc, I am not prepared for that but anticipating the grin I will have once I get the engine broken in. Most likely run the 18/56 gears with that engine. At least I will have an extra engine to use if needed.

 

[davehour]

Well CY engines are just very low quality and the carbs are a clone of walbro from what I’ve been told but how I’ve been doing it is run what ya brung til your tired of f$$king with it and upgrade…I never thought there could be such a difference between CY and zennies but you just can’t beat the Japanese when it comes to 2 strokes hell any small engine and they run great…funny iVe got 2 36’s sitting in a box and one only has like 2-3 hrs of run time…just keep them around in case but Think im gonna build a shitshow basher for my buddys to beat…lol

Here a video of that engine in my Losi I took today in the snow…she starts bogging a bit with the extra ten lbs of snow in the chassis and a soggy air filter

Does the two speed hold well the offroad and bashing beating?

 

[DonnieD]

Well it’s a Rovan 2 speed and after a couple mods right out of the box so far it’s awesome having it…but WHEN it fails I won’t be buying another for the Losi anyway..Baja definitely putting one in it
Sorry thought u meant me lol

I had a good opportunity to run the Rovan today. 58/16 gears, 7k clutch spring. New spark plug. I was running way on the rich side previously, so I did make some adjustments to the carb yesterday morning. Started at defaults. I did not have to make any adjustments today and the engine ran without issue. No leaks around the spark plug or along the head casting seam. Ran the tank dry (almost). WOT, the rear loses traction. Damn Rovan tires. Thinking on the Duratrax lockups since the viper and others are sold out everywhere. What I have now is just ok but they do much better than the stock treads.

I am not running any screens on this one yet. I did cut away the melted plastic on the cowl. I left as much as possible so there would be no forced air in the direction of the carb. I did not feel like putting the body or rear wing on the car if I needed to remove the engine if what I thought was correct and the head was cracked. Performed well actually.

If the Zenoah with 34cc stroker is more of an engine than the Rovan 36cc, I am not prepared for that but anticipating the grin I will have once I get the engine broken in. Most likely run the 18/56 gears with that engine. At least I will have an extra engine to use if needed.

Ya it will…my Baja just has G320 with ESP race ported cylinder and runs great

 

[Bandit2013]

The King Motor 2 Speed for the Baja 5B types works ok. My mistake during first assembly is I had the catch claw part in backwards so the 2nd gear was not engaging. I bashed the hell out of it running only the one-way bearings on the 57 gear. Once I realized it was not shifting, I flipped the shifter around. Took some time to find a good shift point for the 36cc due to lower RPM range. Reason why I went to singe gearing for the new build and for the Rovan limited. I did buy another 2 speed gear set to use on the Rovan but opted not to use it since the performance was good with just single speed. Less to wear out and better fitment to the body. Most of the 2 speed parts I started with will be reused. The blown bearing on the bell came with the gear plate assembly. Easy to replace once I can get it free from the shaft. May need to use a heat gun to get it off since I used red thread lock on the screw that holds the shaft to the bell. It is a two-part shaft but secured from the back side of the bell. What comes with the kit is an extra set of gears. The gears that are not assembled are the 22/52. The 20/54 is the second gear assembled onto the hub and the other is the 17/57 for first gear. I did attempt to swap the gears but could not free the one screw before stripping out the hex. Had that so hot I could not touch the damn thing but to no avail could I get the last screw out. Also, I did not want to overheat the bearings. Next time I will use a heat sink on the bearing assembly, will have to make one with something or figure out how to remove the bearings without damage. May try this with the new set and see if I can manage the gear swap. Curious what the 22/52 will do. The only issue I have heard about was that some have gotten the set with the one-way bearings installed backwards. The two spur gears have mating surfaces that mate in one direction only. If the one-way bearings in the first gear hub are in bastardly it will not work.





Once I did get things set up I was happy with it. Beat the hell out of it for a few weeks prior to slamming into a wall with the car. Bummer. For off road use and loss of tire traction the 2nd speed will kick in due to wheel spin as this is based on RPM and spring loaded grabber. I will learn more on this with the King Motor 30.5cc engine. I assume it will have more RPM than the 36cc engine.



When using off road it is hard to hear the gear change since that happens sooner than expected unless you have really grippy tires. On road, yeah, it makes more of a difference. I am sure there would be more top end with the other gear set for 2nd gear. I feel this gear assembly would have better use on road surfaces than off road. Not sure if my opinion will change once I get some time with the 30.5cc engine. I will not be running the Zenoah with the 2 speed gear set. At least not off the bat.

I opted for the enclosed HD gear/bell assembly. Perhaps not a wise choice due to lack of venting or means of keeping the bearings cool. I fried the bearing closest to the bell. It still rotated freely. Not sure how long it would have lasted before seizing up. There was so much spent clutch material packed in from wear with no place to go. The rubber gasket on the bearing was gone and the metal ring left was intact but not seated in the groove.




The bell housing is sort of vented where the brake pads fit but doubt that was enough. The aluminum filings are from the brake pad hex grinding into the gear plate assembly. Probably my fault as I shimmed the spur gear assembly for good mesh and gear alignment. This brought the brake hex part into the gear plate. Odd that I did not notice this since the assembly rotated well without restrictions. I will use the new HD gear plate assembly for the salvage rebuild project. Drilled out some venting holes on the plate and ran an end mill on the clutch bell spacer. Did a crappy job since the end mills at work were tied up with production support so I tried using the drill press in the engineering fabrication area. Could not get the end mill to run a straight line. I used to have an end mill machine at my disposal in engineering, but the company scrapped it on us and replaced it with a crappy drill press. It does not look pretty but will do the job I suppose.





The stock bell carrier would be a better option. Unfortunate that the heavy duty gear plate will not work with that. I believe there is another gear plate that has improved surfaces for the layshaft bearings. Turtle Racing has similar design which is what I decided to run with the other cars. Again, sealed clutch bell housing. I vented one of them in a similar fashion to the Rovan parts.



What I have used to break in the gears was this stuff from Lucas oil. Super tacky and slick. Made the gears run very smooth and did not cause issue with the one-way bearings on the first gear. Don't expect it to stay on the gears for long and will make a mess of things as it will leak out. Clean it off once you get a few hours of use on the gears. Probably not needed but I have had good results. Note that the gear cover does not fully seal the gear assembly so dirt and crap will make its way in there. You do not want this stuff to find its way to the clutch bell. Just a small amount will go a long way.

 

[Bandit2013]

I will get the Zen installed in the new build. Taking my time getting the outerwears installed. I still need to do the bottom side of the engine. Since I am using RTV adhesive, I prefilled some of the support extrusions where the velcro gets attached. Perhaps this evening I will be able to get the velcro installed. Soil in my area is more like a fine dust mixed with sand. May as well be on the beach. However, after the rain, the ground becomes as hard as concrete. That fine dust will impede the weight movement in the easy-start unit such that they will not spring inward after a hard run. the outerwears should aid in preventing that.



I was surprised to find that the RCMAX starter will work with the Zen without any mods to the flywheel. That is cool. Also wanted to try a better velocity stack with clamp on filter. As for the other Rovan 36cc, that will be used as a standby engine in case the KM 30.5cc engine is an epic fail as it was when I first tried to get things started. First thing I did was bust the pull start. I had a similar feel with the stock Zenoah pull start. That compression stroke on the piston makes it difficult to get a pull since most of the rip cord gets waisted extending the telescopic paw. The acetone is to clean the metal surfaces before installing the velcro or RTV adhesive. It was cheaper to buy it at walmart than getting it in a can from Lowes since I do not use much of it but does make for a good cleaner for parts. Try not to buy that stuff with oils in it, look for 100% acetone. Not sure what is with the blue dye but it does the job. The Killer Bee kill switch is installed. I decided to reuse the yellow Zen switch as it is sealed on the back side vs the ones used by Killer RC. They are not that expensive if you look at other places like Digikey for electronics. I did have to take off the fan cover to get to the coil terminals as they are tucked in quite well.



I may reuse the cover I have on the other motor since the filter sock seems a bit long. Note: for pull start handles, opt for plastic over aluminum versions as they weigh a bit less and are usually smaller. I found the aluminum versions tent to flop over and could potentially become an anchor if the starter spring craps out, or if you run the car into some small trees or saplings, tall grass or vines. Probably more of an issue with a Baja than say Losi or Kraken.