Ugh..... I'm stumped

sirsumm · Apr 14, 2006

My beast may have me beaten. I have had carb problems for a while now, and posted about them here, and received allot of helpful advice so far. unfortunately I am still having problems. The strange thing is that once I solve one problem others seem to appear. I started with a lean condition at high RPM, this wound up being the needle and seat sticking closed. I changed out the needle and seat, and things worked super for a day. Now I have a lean condition as best as I can tell on low (1/4 throttle or less). My bike has no power at all in lower RPM's. I assumed that I had a clogged idle circuit, but can't seem to find anything plugged. When I turn the mixture screw I have little to no effect on the engine speed or lack of bottom end power. This morning I decided to adjust my valves thinking that might help. This changed the RPM's that the flat spot started at, the flat spot ends sooner now, but also seems more severe. My exhaust now sounds more sharp and crackly at an idle, and it is possible to almost stall the engine if I apply throttle too soon. I am at a loss, as to what is wrong. I was sure that I had carb problems, but now I wonder if I have cam or valve problems? Anyone have any ideas? I am now seriously considering taking the bike in to a local tuner to get his opinion. I would rather fix it my self, but I lack experience in diagnosing these symptoms. HELP!!!!

nsman · Apr 14, 2006

Re: Ugh.....I'm stumped

A possible cause.
The sticky needle and seat assy caused the mixture to lean out at higher flow rates(high rpm),this extra heat resulted in a burned valve or valve /seat damage.The change of the needle and seat made it seem to run better but as the valve to seat seal was now leaking the damage continued.With this valve leakage a drop in intake vacumn occurs feeling much like a low speed bog,and also becomes unresponsive to low speed carb adjustments.Adjusting the valves may make a slight change in the seal but the damage is now done.
I would recommend that you take it to a good tech and have a" leak down test" done.This will verify that there is a good seal in the combustion chamber.If you have a burned valve or warped valve seat you can often hear the leak.If you have a good reading then you probably still have carb issues .

sirsumm · Apr 15, 2006

Re: Ugh.....I'm stumped

That seems to make sense, it's just not what I wanted to hear. I will get the bike into the shop this week, and have the leakdown preformed. How serious is this? Am I looking at replacing my entire head, or getting a valve job? Or is it possible to use lapping compound to correct this issue. I am sure it all depends on the extent of the damage. Darn it, seems like I work on the ol girl for 10 hours to ride 1. So if the worst case is that I have to change my head out, where can I find one? I have yet to see a head listed on Ebay here in the states.

whosahberg · Apr 15, 2006

Re: Ugh.....I'm stumped

i would take the bike to a professional tuner and get his opinion on what the problem could be .

it could be fuel . electrical , or mechanical .

find out what is the definite problem , the cost of getting the advise of an expert will save you money in the long term .

fe600racer · Apr 17, 2006

ok the 95 had flat slides, so check the condiition of the needle. You need to take it out of the slide and see if it is warn. The jets wear out also.

I think the problem will be the sem ignition though. you need to borrow a new or reconditioned one and try it. this is quick and easy and I think will be the answer. there is no one thing that you can look for, but often ignition failure mimics carb problems. Make sure your roller rockers are in good condition on the top end though.

sirsumm · Apr 17, 2006

When the rain stopped this weekend, I decided to attempt to diagnose the problem with a compression tester. I learned 2 things:

1. With the auto decompression connected, I don't learn anything. DUH!!!

2. Without the decomperssion connected, an elephant couldn't kick this bike over. I weigh 260lbs and was standing on the kick start lever.

I suppose I need to actually take the bike in, once I check the things that fe600racer suggested in the last post.

dsducati · Apr 17, 2006

Take the pilot jet out and spray contact cleaner through the jet to be sure it is clear and into the carb body making sure the contact cleaner comes out near the front of the slide in the carb bore. Also, up to 1/4 throttle you are running on the straight part of the needle. It waking up at 1/4 throttle may be due to the needle pulling into the tapered area and finally richening things up. The needle jet can get coated with a layer of varnish if it has sit too long and cause what you are experiencing or maybe the needle jet is simply too small.
dan

Ugh..... I'm stumped

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