89 rm 250 Loading up, hesitation, no idle, bogging bad

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#16
The black plug could be water from a leak in the cooling system into the combustion chamber. A leak down tester can help, and it will check the crank seal condition. The right side is good for spooge. You can not look at a float valve and assume its fine. You do not even have a guarantee by leaving the bowl off and pushing the floats up, that it will work correctly. Just replace it yearly, or when you are having screwy problems. And stay with oem parts, keep it simple, you do not need more variables like crappier parts. An 89, does it have a power jet also? And for pete's sake, dropping the oil ratio to 40 is effectively increased the amount of gas! You made it richer yet? Premium fuel, factory oil ratio, factory jetting, replace the float valve, have a leak down test done.
 
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#17
whenfoxforks-ruled said:
The black plug could be water from a leak in the cooling system into the combustion chamber. A leak down tester can help, and it will check the crank seal condition. The right side is good for spooge. You can not look at a float valve and assume its fine. You do not even have a guarantee by leaving the bowl off and pushing the floats up, that it will work correctly. Just replace it yearly, or when you are having screwy problems. And stay with oem parts, keep it simple, you do not need more variables like crappier parts. An 89, does it have a power jet also? And for pete's sake, dropping the oil ratio to 40 is effectively increased the amount of gas! You made it richer yet? Premium fuel, factory oil ratio, factory jetting, replace the float valve, have a leak down test done.
I figured i would replace the float valve but the guy at the shop wouldnt even sell it to us, he said our valve was fine and we didnt need it. Probobly just wanted us to drop the bike off and pay him 70 an hour to look at it. As far as the fuel ratio goes its been at 32:1 to startup to 40:1 and back down to 32:1 again. The thing that i am having a hard time understanding is when i shut the petcock off the fuel level will run down and the bike idles perfect for 5 seconds so that is telling me that its a fuel level problem. I can think of anything else that will cause the level to be high when the float has been set and measured 4 times. Its at 14 mm to the casting line on the floats. You pull the plug and its very wet everytime. I dont have a leakdown tester on a compression gauge so it looks like it destined to go to the shop.
 
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#18
Uh. Replace the float valve? And stay away from that shop! You can order the right valve from sudco, but you'll need to make a 15 dollar order. Add in a couple jets larger/smaller than what you have now to make a full order.

I like your method of running the fuel petcock partially closed, that is a good hint that the problem is indeed overfilling the carb with fuel. Have you checked that all the carb vent hoses are free of obstructions? If it's overfilling that badly you should have some fuel running out of the overflow, assuming it's not clogged up.
 
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#19
The vent hose isnt clogged up. If you lay the bike over to about 45 degrees on the petcock side the fuel will poor out of the overflow as usual. I might try to mess with it again before i have my friend send it to the shop. Ill probobly at least order a check valve like i thought we should try the first time
 
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#21
Ive got one more question. Is there any way the cylinder could be taking water in and not cause bubbles in the radiator when running? I have a float valve ordered and ill try that when it gets here and let everyone know if it helped. Also im thinking of making a video of the bike idling and running if anyone here thinks that might help them diagnose this.
 
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#22
You tell me, does the 2 hoses come off the pump and feed the head/cylinder, or seemingly pumps through the cases, and up through the cylinder. Look in the book for the normal operating pressure, or the cap, and pressurize the system with air? If it feeds into the cases take your pick, center case joint, base gasket, or a cracked cylinder/head or case. A leak above the compression would be the only one that produces lots of bubbles, I figure. Are you loosing a lot of fluid? A black plug can be from retarded timing, or incredibly rich jetting, low compression, bad right crank seal, or its been ported and polished?
 
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#23
I guess this thing is gonna have to go to the shop. We went to a local shop today to get a float valve so i took ours in to match it up and they said there was no way that thats our problem and the valve we had was fine. I put it all back together and set the float again and its doing the same crap its been doing. I dont know what else to try other than split the case, do a complete rebuild and buy a carb for it. It would be my luck that wouldnt even take care of it :bang:
Hi did you solve the bogging down problem. Having identical problems with same outcomes ... the bike runs strong when partial turn off of fuel .. float valve etc all been done still no clean run.
Air cleaner element to replace next see if that alters anything
Thanks.
 
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#24
Hi did you solve the bogging down problem. Having identical problems with same outcomes ... the bike runs strong when partial turn off of fuel .. float valve etc all been done still no clean run.
Air cleaner element to replace next see if that alters anything
Thanks.
I just did my brass on my 89 cr-fiddy, I leaned em out 1 step, it seem to run a little crisper. I have a kehin on it so it was easy to change them out. Pull your plug, if it looks like a charcoal biquet its too rich, if it is white and blistered its too lean, if the center electrode is carmel then its jetted perfect!