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Engine Sputtering


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#1 Rob7620

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Posted 16 April 2019 - 12:20 PM

Hi all

 

I have an issue with my 1275 at the moment. It has recently come out of hibernation and has decided to develop a sputter and loss of power at low rpm under load in 3rd and 4th mainly.

 

I have cleaned the carb out and fiddled with the tuning a bit which doesn't seem to do much if anything.

I have also cleaned the plugs and ht cap to no avail.

I have not changed the timing as that was fine last year and it has not moved since although if all else fails I may have to give it a go.

 

Do you guys have any suggestions on what else I can try?

 

Thanks in advance



#2 SuperDeLuxeNick

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Posted 16 April 2019 - 12:41 PM

almost certainly crap in the fuel where its been sat. clean the carb again and the float chamber and especially around the jet etc.

 

then put new fuel in and fit an inline fuel filter (worth it anyway for £5)

 

Hope that works



#3 cal844

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Posted 16 April 2019 - 12:48 PM

Drain and fill the fuel system with fresh fuel. Fit a fuel filter as said above, see your local MOT centre for one or buy then on ebay

Edited by cal844, 16 April 2019 - 12:49 PM.


#4 Rob7620

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Posted 16 April 2019 - 01:59 PM

Hi thanks for the replies
Forgot to mention i had fitted a new cleaned tank with a filter so not an issue with dirty fuel.

#5 KTS

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Posted 16 April 2019 - 04:50 PM

distributor advance not operating correctly maybe ?

 

check the vacuum advance mechanism works, if that's ok maybe check the advance weights aren't sticking



#6 luismx123

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Posted 16 April 2019 - 07:10 PM

Could be temperature related. Mine goes really lean down below 2.5k rpm but once it's warmer the power band works from 1.5k up. still slight sputters but that's due to the needle being too lean. Hope this helps

#7 Rob7620

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Posted 16 April 2019 - 08:13 PM

Thanks for the advice, I ended up trying to fiddle with the mixture screw some more, changed the dash pot oil again and put new plugs in it.
It seem to be sorted now but I don't know which fixed it! 🤦‍♂️

#8 luismx123

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Posted 17 April 2019 - 07:26 AM

Thanks for the advice, I ended up trying to fiddle with the mixture screw some more, changed the dash pot oil again and put new plugs in it.
It seem to be sorted now but I don't know which fixed it! ‍♂

I found out that my sputtering at lower rpm was caused by it running to lean. At higher revs, it seemed fine. Hence why I got some various oils for the dashpot and Im currently testing them out to see whats the difference. The thinner the oil/the less you have in there, the quicker the piston will rise under acceleration causing the mixture to lean out more than you'd want. You might have just been completely empty :/






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