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Post by tigertail on Aug 31, 2014 13:19:22 GMT
A few days ago I commuted to work on the old gal, as reported on the Maiden voyage thread. When coming to a halt the revs would "stick" at 2500rpm unless I slipped the clutch out a little to bring them down. Once they were down they would stay down until the next time I pulled to a stop (or pulled in the clutch and coasted). Although the tickover was hunting a little I couldn't reproduce this fault on the driveway, only after riding the bike for a mile or two would it re-occur. Spraying Easy Start around each carb stub didn't make much difference, the tickover was continually up and down by a hundred revs or so anyway.
Thanks to Stevellews suggestion on the other thread I took another look at the carb mounts and after removing the side panels and staring at it for a bit I realised that at the airbox side I could see a rim on the carburettors that should have been under the rubber mounts. This meant that there was only a very small amount of the carb stub inside the rubbers. how I had missed this previously god only knows. So after loosening the clamp screws, sat astride the bike and gave the carbs a pull back/wiggle to reseat them further back, retightened the clamps and hallelujah all is good once again. Tickover is now steadier than its ever been and after a good ride the revs fall back to a steady 12-1300rpm and I am once again a very happy chappie.
I can only put it down to the vibrations and bumping as I ride along that was causing the carbs to break the otherwise airtight seal, still cant figure why it would drop back to normal after a bit of engine load though-maybe the extra vacuum effect caused it to reseat the seals. So big thank you to Stevellew, you were spot on the money!
TT. |
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Post by grahamb on Aug 31, 2014 14:11:17 GMT
Good to hear it was a simple fix  |
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Post by scania on Aug 31, 2014 22:07:54 GMT
Can you clarify for me,
Was it the seal between the carbs and the airbox that was loose ?
or
was it the seal between the carbs and the cylinder head that was loose ?
I would be surprised if the seal between the carbs and the air box had much effect ?
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Post by tigertail on Sept 1, 2014 5:42:30 GMT
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Deleted Member
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Post by Deleted on Sept 1, 2014 8:20:43 GMT
Great that it's sorted.
My revs on my 250 also hang a bit.
I will check what but I am suspecting the O-rings within the inlets on mine. Will be taking the carbs off over the autumn / winter and checking them out as well as other things.
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Post by tigertail on Sept 1, 2014 10:25:58 GMT
Can you clarify for me, Was it the seal between the carbs and the airbox that was loose ? or was it the seal between the carbs and the cylinder head that was loose ? I would be surprised if the seal between the carbs and the air box had much effect ? Like you say, the seal between airbox/carbs shouldn't make much difference when you think about it. All I know is that reseating the carbs was the only thing that I did and the problem went away. It is possible I suppose that something else was disturbed when the carbs were slid back 1/4 inch and it was that causing the problem rather than an air leak. TT. |
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Post by stevie on Sept 1, 2014 12:41:01 GMT
Simple test for air leaks around carb area, spray carb cleaner around rubbers with engine running, if revs pick up then die you have an air leak and i would think it would cause various running problems
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Post by tigertail on Sept 1, 2014 13:46:42 GMT
As stated above, spraying easy start around the carbs on the driveway had no noticeable effect. Spraying it while riding along at 50mph seemed a little OTT ;-)
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Post by stevie on Sept 1, 2014 14:06:03 GMT
Yep your right lol, didnt read the full thread, glad you sorted it in the end
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Post by stevellew on Sept 2, 2014 8:16:45 GMT
Glad you've sorted it mate
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Post by scania on Sept 4, 2014 18:21:11 GMT
I must try to create this condition some day and see can I get the same effect, maybe the carburettor was put out of balance some way as it did no have to pull the air through the air filter.
It is good to know about this, in case it ever happens in the future.
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