engine heats up quick & dies, please help

[pliebo]

my new RB tm 928 is just broken in & ever since I got it I noticed it heats up to the 220 point really quick I didn't nt5hink anything of it when Iwas breaking it in but now it won't run longer than 5 minutes and dies every time it reaches around 220. I took apart, inspected & cleaned the carb tonite maybe that'll help. please help me with some clues to why this is happenning, thanks

 

[vbgagnon]

Seal it with rtv sealant. Carb, and backplate. Also Your lsn is prob too lean. richen it up a bit and try that.

 

[pliebo]

thanks, I'll try sealing the backplate cause I did put the rotosatart conversion on & maybe it's leaking. also is it ok to just put silicone around the carb base? I did notice too, that when it gets up around 220 it starts revving higher & sounds really lean. does lsn effect high revving engine ?

 

[pliebo]

okay I just sealed the backplate & carb with silicone gasket sealer hope thats ok. will see what happens tomorrow. whats the best way to check for air leaks ?

 

[HeartBreak]

I usually load the engine up with after run oil, then plug the exhaust port, carb intake, and use a small piece of fuel line on the fuel inlet nipple. I then stick the spray tube from a can of compressed air in the fuel tube, then give it a gentle blast.

You have to have a glowplug in the engine, for obvious reasons, of course.

If you have an air leak, you should see oil bubble out.

If the engine is a pullstart/rotostart engine, remove the pullstarter first, so you can see if the airleak is from the starting shaft.

 

[pliebo]

thanks I'll try that next, I sealed everything as said before and it's still doing the same thing, heats up quick to 220 then revs up real high and sounds really lean no matter how rich the main needle is. I put a carb from an old p5x tonite to see if the problem is in the carb or the engine( I think I may have bought a used engine dressed up in a new box) somebody broke it in wrong & cleaned it up and put it back in the box! It didn't have the celephane RB wrapper. thanks for any other advice I could get, maybe I can fix it

 

[jon2]

Just got to throw this out but have you checked the fuel and pressure lines for cracks or tears? Also is there a brass collar under the plug? Do you know ifd this broken in with 20% or 30% or something else?

 

[kx250ryder]

Make sure that your HSN isn't too lean and being masked by your low speed needle being too rich.

Warm your car up by driving it (not idling it), then bring it in, pinch and hold your fuel line until the engine dies. It should take between 3-5 seconds (more like 5-7 during break in to be on the rich side) for the engine to die. If it takes less, the LSN is too lean, if it takes more, the LSN is too rich.

Once the LSN is set properly, go back and check the HSN settings to get the temperatures in range.

EDIT: A good rule of thumb would be:

Break in:
200-230
pinch in 5-7
idle as high as possible without making car move

normal running:
230-250
pinch in 3-5
idle as high as possible without making car move

 

[pliebo]

broke it in with 20%, there is no brass washer under the plug cause it's a turbo plug ( they don't use the washer do they?) and I've replaced the fuel and pressure lines. as of today with the new carb it ran better cause it was running nice and rich but it just took longer to heat up and once it got to the 220 area it died,,, continuously. I think either I broke it in wrong or got a used engine. maybe the piston sleeve fitting is not tight and when it heats up it loses compression?

 

[[email protected]]

I'm actually having the same problem with my OS 18 cvr engine. I still haven't figured it out I'm trying every trick in the book I'm about to touch the msn. i read the article in one of the new issues of one of the magazines of how to tune the msn. If you richen the msn lean your lsn the same amount. But not only does my engine get up to 240 fast but it cuts out quick when i give it throttle, a horrible bog. So the mag says to lean out the msn and richen up the lsn when this happens.

have you given it some thorttle on the ground and found out how the tune is?