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Post by tristram on Mar 8, 2024 8:46:19 GMT -5
Many thanks for the tap-the-float-bowl suggestion. Unfortunately this made no difference. I am going to take your and stevep's original advice and get a new carb. In the process I have noticed more things that need attention (thank you gotsron) and have promissed the bike I will deal with them once new carb on.
Thanks you also to sr500 forum for the opportunity to tap into wiser and more experienced heads than mine! This will not be my last cry for help!
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Post by stevep on Mar 8, 2024 9:05:12 GMT -5
It's possible reading your last post, that you didn't quite get what gotsron & Andy were saying; if you have a vacuum petrol tap on your fuel tank, you need to eliminate the possibility that fuel is getting into the short vacuum tube between fuel tap and inlet manifold. In other words the fuel tap diaphragm is leaking. This leads to an excess of fuel bypassing the carb altogether! You can sub a piece of clear tubing for the vacuum line and see if fuel appears during idle. No amount of carb tuning will help if that situation is going on.
If you don't have a vacuum type fuel tap (straight on/off) this check won't apply.
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Post by andy on Mar 8, 2024 9:36:03 GMT -5
Explained perfectly accurately Steve 👍. Just hoping collectively we can save Tristram the cost of a new carb and the bits and bobs getting it all fitted and dialled in.May be losing the battle at the minute….we’ll see .
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neal
Junior Member
We may need a bigger hammer.
Posts: 37
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Post by neal on Mar 8, 2024 14:26:02 GMT -5
Lads,
I am by no means a carb expert, so up to now I have been a little reluctant to offer any advice. I am however running a VM34SS and had, like most others, issues getting it working properly. I ended up replacing petcock to a non diaphragm item, putting in a keyster repair kit and replacing all diaphragms. Carb is pretty spot on now ( I re-jetted and raised needle one notch to suit K&N and new pipe) but the money I have spent sorting the bugger would probably have been better invested in a VM34 as Andy has suggested. VM34SS is an over complicated design on a motorcycle designed to be simple and uncomplicated. All subjective of course, there are lads that love them. I am not among them.
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Post by andy on Mar 9, 2024 3:15:59 GMT -5
.... but the money I have spent sorting the bugger would probably have been better invested in a VM34 as Andy has suggested. VM34SS is an over complicated design on a motorcycle designed to be simple and uncomplicated. All subjective of course, there are lads that love them. I am not among them. It was many years back my stock carb was playing up but to be honest I never looked into the petcock possibilities and who knows ? that could have been the problem. I did manage to sell it on e-bay to offset a bit of the price of the new vm34.To sum up the saga I have total confidence now, compared to always feeling a bit edgy with the stock carb..will it tick over? will it start ?will it run right ? Subjective ? that sums it all up neal ! |
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Post by tristram on Mar 13, 2024 11:00:52 GMT -5
Just taken the plunge and ordered a new VM34 (thanks Steve of Motocarb). Just for the record I had tried to see if there was any sign of petcock diaphram leak (not a phrase I want to use often) as suggested but tested negative.
I hope others in the future are helped by the responses here as much as I have been.
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Petes2Wheels
Full Member
Out riding the country roads
Posts: 102
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Post by Petes2Wheels on Apr 5, 2024 21:36:11 GMT -5
I have an original cycleserv publications yamaha sr500 manual published in 1979. From the looks of it and the notes in it would guess it is from a Yamaha dealership. It has all the tech specs and clear instructions on the whole engine and very detailed on the VM34ss carby.
If you need any factory specs for your rebuild to get it at stock settings let me know.
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