Author Topic: Lack of engine power  (Read 1200 times)

Offline Felters

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Lack of engine power
« on: 15.02. 2012 20:18 »
Was out testing my new SRM clutch yesterday when the bike suddenly seemed down on power. It would rev ok in neutral but I was struggling to get the bike over about 45mph in any gear. I'd just filled the tank - although it only took about a gallon - and as soon as I got home I whacked a new pair of plugs in. Made no difference.

I've got a feeling it's probably the carb - the magneto has just been rebuilt and it normally starts first time so I'd be surprised if it was electrical. Any bright ideas?

PS The SRM clutch pressure plate is a "good thing".
'59 BSA A7 and '02 BMW 1150RT

Offline t20racerman

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Re: Lack of engine power
« Reply #1 on: 15.02. 2012 20:40 »
If it packed up straight after you filled up I'd check your fuel for contamination. You can get water at the very bottom of a fuel pump tank. Drain the float bowl and see what is in there.
Also, what are your plugs like?
1961 A10 - somewhat modified :-)
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Offline Felters

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Re: Lack of engine power
« Reply #2 on: 15.02. 2012 21:00 »
The plugs I pulled out looked ok - if the temp get's up a bit this week I will give the carb a severe looking at.

'59 BSA A7 and '02 BMW 1150RT

Offline wilko

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Re: Lack of engine power
« Reply #3 on: 15.02. 2012 21:10 »
Timing slipped?

Online bsa-bill

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Re: Lack of engine power
« Reply #4 on: 15.02. 2012 21:56 »
Clutch slipping ??
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online orabanda

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Re: Lack of engine power
« Reply #5 on: 16.02. 2012 00:05 »
Compression test would be useful (and easy)

Online chaterlea25

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Re: Lack of engine power
« Reply #6 on: 16.02. 2012 00:19 »
Hi
If the tank was 3/4 full and the ""fuel"" has been standing for more than a month or so, its gone off *ex*
the gallon you added wont help much *sad2*
Drain the tank and start with some fresh fuel
HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Online orabanda

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Re: Lack of engine power
« Reply #7 on: 16.02. 2012 01:29 »
Wilko makes a good point (pun intended) about timing having changed.
Check points gap; should be between 0.012" - 0.015".
If the adjustment nut(s) work loose, the gap and timing will change, and the performance will change quite suddenly, and suffer.
I have had this happen. I now always include a set spanner in the tool kit which matches the nuts (from memory; 1/4" AF) because it is difficult to re-adjust points by the side of the road, without the right tool!

Also, the bakelite heel which follows the cam profile can also wear, with the same result.

Richard

beezermacc

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Re: Lack of engine power
« Reply #8 on: 16.02. 2012 07:03 »
Hi Mike. I've sent you a pm. Give me a ring if you need any help.

Offline andy2565

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Re: Lack of engine power
« Reply #9 on: 16.02. 2012 10:47 »
process of elimination,plugs points timing carb,tank filter,compression,of which i use a leakdown test rig which is better,good luck,it sounds like the mag,but best work your way down the list.
near wolves uk,will keep riding as long as can stay upright,tribsa,tt500,2xJAP grasstrackers+jawa.gold flash.triumph metisse,and others.

Offline Felters

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Re: Lack of engine power
« Reply #10 on: 21.02. 2012 16:21 »
Well who knows? I closed the points slightly to get them to 12 thou, made sure the plug gaps were right, plug leads firmly on - and it still had the problem. Then it seemed to clear itself and it was soon ripping up the tarmac. OK I lied about the tarmac but it was going just fine so hopefully that's it. Whatever it was.

Mind you it was cold and I hadn't put all my kit on so I didn't go more than a few miles - but tomorrow I'll give it a longer run and see what happens.

Cheers
Mike

PS Thanks to Beezermac for his kind offer of help.
'59 BSA A7 and '02 BMW 1150RT

Offline Felters

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Re: Lack of engine power
« Reply #11 on: 22.02. 2012 20:00 »
Cleaned out the main jet bowl - and it did need cleaning. Gave it a good 25 mile run round the local country roads and all is well. A lesson learnt.

Many thanks for all your help.

Mike
'59 BSA A7 and '02 BMW 1150RT