Overheating Damage?

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MonsterAir

MonsterAir

Lone Racer 🤠
Messages
2,369
Location
Long Island NY
Just got done breaking in my motor, did 2 high speed passes at 40% throttle and my engine cut out. Ran over took a temp reading and it was 320deg!!! Now I can't seem to get it going under load. Meaning when I lift the tires off the ground she perrs but try and take off on the ground and she boggs out. Could I have warped my head during those 2 passes? Probably over 280deg for under 5 min. Such a nightmare. Problem after problem with this thing. Ya ya I know I caused this one but damn, so much fun but so frustrating at the same time.
 
If its a Zenoah, I doubt it - done it myself.
If its still hot, might be a vapour lock - pump the fuel through a bit using the primer.
If no good, check the carburettor settings - 1 1/4 low, 1 1/2 high are approximate settings, then tune a bit.
If still new, needs to be a bit rich.

If it did get too hot, check the plug - might consider a plug change.
Al.
 
Thanks Al. Ya it's a Zenoah 2 bolt. I let her cool down a bit and was able to get it running smoothish again. Such a roller coaster ride with these things for me....... Question, do I have to tune differently for speed runs compared to shorter runs with more stop and go? I seem to have the temp under control (220-260) when bashing in a smaller space but when I open her up for some distance the temp jumps up. Should I be adjusting the needles when going from one type of driving to another or am I just not dialed in with it yet?
 
Tune it right, that's it.
If you continue to simply have it screaming at top revs, may have to consider how to get air to it, and PERHAPS enrich slightly - not enough to change power but a little extra fuel may cool it better.

Al.
 
How does your engine run, Have a friend that could not afford a mod engine so he went with a Rovan engine, i think it was a 30.5 cc. Any issues!!!]
 
MonsterAir said:
Castor 927 @ 25:1 is what I've been running. Maybe I'll try a bit more oil on the next fill up.
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I have read on a couple of different sites that adding more oil actually leans it more. In theory it makes the fuel thicker and thus less of it can get through the tiny jet hole. I have no clue if that is true or not, but does kinda
to make sense.
 
MonsterAir said:
Just got done breaking in my motor, did 2 high speed passes at 40% throttle and my engine cut out. Ran over took a temp reading and it was 320deg!!! Now I can't seem to get it going under load. Meaning when I lift the tires off the ground she perrs but try and take off on the ground and she boggs out. Could I have warped my head during those 2 passes? Probably over 280deg for under 5 min. Such a nightmare. Problem after problem with this thing. Ya ya I know I caused this one but damn, so much fun but so frustrating at the same time.
Click to expand...
Hmm not sure that two passes would be enough to do serious harm.However maybe the high heat damaged a gasket or warped the intake manifold. Your likely just going to have to go over everything and see if anything shows. Its a PITA dealing with mysterious issues. Hope you get it sorted out soon.
 
Todd5b said:
How does your engine run, Have a friend that could not afford a mod engine so he went with a Rovan engine, i think it was a 30.5 cc. Any issues!!!]
Click to expand...

I just finished braking it in. OBR said that 32:1 with a good oil (castor 927) is cleaner. They are sowing two pics of the piston on their side: one with kloz and the other with castor 927. They recommend castor 927 . I am new at this so I have to listen to them. Will see how it will do. I ordered another OBR (the same, a spare) and zenoa full mod cat5 all with 990 carb. Want to compare. I already see a difference between obr and cat5. cat5 s ideling is different. had to close the idle scrue all away or it dies. Whith obr I have the scrue have way and and it idls much stronger. alsow with obr I have to run richer .
 
Thanks for all the responses guys. Motor is still reaching temps of 280-320. Starts to lean itself out around 300deg but I really have to be on it for that to happen. I'm at about 280 after a hard lap or 2. I've tried gearing it up but it even runs hot after a long straight with 26/38 gearing. I have yet to try less oil, next time out I will give 32:1 a shot and see how that effects the temp. If that don't work I guess I'll try changing the gaskets some time this week.
 
Trebor said:
25:1 is fine ......just richen up the carb setting

K....
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hi. I have an OBR zenoa ful mod g340 .34cc. I us castor 927. This is what OBR recommends. They want me to run 32:1. I ask them few times and they insist on 32:1. They say it is the best oil and at 32:1 it will be cleaner. What do you think.
 
I run 32:1, when I run it, which isn't often.
I only run for perhaps 20 minutes at a time.
If you're going to run for a few hours, which most do, then I'd revert to the 25:1.
The actual difference isn't that much, but will ensure the engine remains well lubricated.
Just my 0.02
Al.
 
Al, do you say that from experience running for extended periods of time with 32:1? Reason I ask is because I have been suggested 32:1. OBR and a few racers that have been in the hobby for a long while all seem to recommend less oil. They seem to claim it's a misconception that more oil equals better lubrication (to a point I guess). One of the guys who I been racing with runs his at 40:1. His car runs great after a solid morning of racing and is one of the fastest if not the fastest on the track..... Curious to hear your input on that. Would also like your input (knowing your an FG guy) on how accurate you feel the FG Gear chart is? I have all of the gears now and none of them have matched the chart speeds. 18/46 I'm only hitting 26-27mph, 20/44 gave me 33mph, 22/42 hit 42 and 26/38 hit 53. Running with a 16t layshaft gear and 48t diff. All of those gear ratios are a solid 10mph off what the chart says. I've been running with the sportsline tires but when I tested with the baja tires w/ 18/46 I only hit 29mph, not much of a increase. Sound slow to you?
 
MonsterAir said:
Al, do you say that from experience running for extended periods of time with 32:1? Reason I ask is because I have been suggested 32:1. OBR and a few racers that have been in the hobby for a long while all seem to recommend less oil. They seem to claim it's a misconception that more oil equals better lubrication (to a point I guess). One of the guys who I been racing with runs his at 40:1. His car runs great after a solid morning of racing and is one of the fastest if not the fastest on the track..... Curious to hear your input on that. Would also like your input (knowing your an FG guy) on how accurate you feel the FG Gear chart is? I have all of the gears now and none of them have matched the chart speeds. 18/46 I'm only hitting 26-27mph, 20/44 gave me 33mph, 22/42 hit 42 and 26/38 hit 53. Running with a 16t layshaft gear and 48t diff. All of those gear ratios are a solid 10mph off what the chart says. I've been running with the sportsline tires but when I tested with the baja tires w/ 18/46 I only hit 29mph, not much of a increase. Sound slow to you?
Click to expand...

Not speaking for Al, but remember the comparisons.
Boat guys run decent periods of time, and 90% of it nearly wide open.
They will mix 8 - 10 oz of oil per gallon in order to keep their engines cool, and keep them from having lean engine issues.

Higher RPM will require more fuel, which carries the oil, which cools the engines and lubricates under high heat conditions.

Other question is where are you taking your temp reading at, because that alone can be giving you false High temp readings ?
 
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