Author Topic: Pushrod question - problems starting new engine  (Read 9037 times)

Offline Duncan R

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Hi All,

Had my bottom end rebuilt and have now fitted the cylinder head and rockers. Had a nightmare getting the pushrods located, but learnt alot so next time should be easier. I cannot get the engine to start, all I have had is few backfires and spitbacks through the carb (after the backfires I switched HT leads over and got the spitbacks)

Due to the fact I had so much hassle getting the rockerbox on I was wondering if its possible to end up with the pushrods in the wrong rockers i.e. exhaust rod into an inlet rocker and so on, I used the pushrod comb and fiited the two long exhaust rods in the centre. All the valves open and close and I have set the clearences and there is no strange noises and engine turns over freely.The tappet adjusters seem very long, are they normally like that? I ask this because I thought I had an A7 and it turned to be an A10 and was wondering if they left the A7 rods in there and put long adjusters in to meet the shorter rods, anyway it ran before like that

I have checked the following

points gap 12 thou
New spark plugs - 2 fat blue sparks when turning the mag over by hand
Fuel is reaching the plugs - cleaned pilot jet and fuel level is ok.
Ignition timing is 3/8" BTDC
Compresion is good - new pistons and rings and rebore.

Thanks for yor time

Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Online muskrat

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Re: Pushrod question - problems starting new engine
« Reply #1 on: 10.02. 2011 20:09 »
G'day Duncan,
                   A7 pushrods are about 1/2" shorter so it would be near impossible to use them in an A10. Two long ones in center for exhaust. Bugga of a job even with the comb.
 Try retarding the timing back to 5/16"
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Online chaterlea25

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Re: Pushrod question - problems starting new engine
« Reply #2 on: 10.02. 2011 20:44 »
HI Duncan,
It is possible to see the pushrods sitting into the rockers if you remove the tappet covers and use a strong torch,
I found a LED one seemed better ????
Once it happened to me that the pushrod sat on the edge of the edge of the rocker cup *eek*
I could see that one tappet adjuster was way different to the others
When you say the tappet adjusters are very long, do you mean screwed all the way towards the valve or away from the valve????

A lot of times newly rebuilt engines or ones which have sat for a long time are hard or impossible to start on the kickstart ???? ???? ????
Have you put fresh petrol in it?
Once you are satisfied that the pushrods are ok, I would try push starting it, enlist a strong accomplice to give you a hand

HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Duncan R

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Re: Pushrod question - problems starting new engine
« Reply #3 on: 11.02. 2011 06:22 »
Thanks guys,

I spoke to the chap who rebuilt the bottom end for me last night, he also said that the engines can be a nightmare to start after a rebuid and they can go either way - start straight away or need coaxing into life.

Pushrods are def located, there is prob nothing wrong with the tappet adjusters they just look really long compered to what I have seen in japanese and German engines.

I will start going through everything again and adjust timing to 5/16.

Cheers

Duncan
Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Offline bikerbob

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Re: Pushrod question - problems starting new engine
« Reply #4 on: 11.02. 2011 09:52 »
Hi there
I don,t know if it will help but a number of years ago I replaced my pushrods and could not get the bike to start the only thing that I had changed were the pushrods. I removed the rocker covers  and on the inlet cover I noticed 2 marks which coincided with the adjusters, the new inlet rods were slightly different in size which was not allowing the inlet valves to close fully I replaced the inlet valves with 2 original steel valves and have had no further problems. So maybe you could look to see if there is any marks on the rocker covers. 

Offline Goldy

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Re: Pushrod question - problems starting new engine
« Reply #5 on: 11.02. 2011 10:04 »
Don.t want to state the obvious, but you are tickling the carb?
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

Offline bikerbob

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Re: Pushrod question - problems starting new engine
« Reply #6 on: 11.02. 2011 19:56 »
Hi there just noticed a mistake in my earlier reply should say replaced inlet pushrods not valves. Sorry.

Offline Duncan R

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Re: Pushrod question - problems starting new engine
« Reply #7 on: 11.02. 2011 20:46 »
Hi Goldy and Bikerbob,

Yes the carb has had a good tickling, it is a concentric and does not  have a choke (air slide fitted) for some reason, I think it was an optional extra when I bought it awhile ago from Surrey Cycles, as I was in a warm climate at the time I opted not to buy it. Pre-rebuild it always started quite easy even with the state of the internals.

The pushrods are the original ones - no obvious wear that I could see also cam followers are original as they were in good condition,likewise the cam. Deffo worth a look at, I am going to measure  each valve depression to get a rough idea if all the valves are opening an equal ammount.

I took all the adjusters out of the rockers as some of the locknuts had a few burs on them so I cleaned everything with a needle file, so of course the vale clearences were set from scratch, checked this by setting the oppisite valve to the one that was open(eg open RH inlet/ LH inlet adjusted) Have I done this correctly?
Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Offline bikerbob

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Re: Pushrod question - problems starting new engine
« Reply #8 on: 12.02. 2011 14:46 »
Yes you are setting the clearances as recommended when one inlet is open set the other inlet  and same for exhaust. It could be because you do not have a choke my A10 will start without a choke in summer but now in the garage in the winter it will not start without using the choke. I also have an A65 which is similar engine wise to an A10 and that will not start at anytime without the choke and you have to keep it choked for short while otherwise it cuts out. So your problem could be the lack of a choke.

Offline Duncan R

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Re: Pushrod question - problems starting new engine
« Reply #9 on: 12.02. 2011 15:02 »
I have been partially blocking the intake off to see if that works - it always started ok with just tickling even in the cold weather. The thing is there is nothing there, cannot hear it fire at all, its not attempting to to run at all apart from the odd backfire or spitback.

I am going to start at the beginning again - check / set plug gaps, valves,timing,points and also get a can of easystart to see if I can get at least some sign of life out of it
Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Offline dpaddock

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Re: Pushrod question - problems starting new engine
« Reply #10 on: 12.02. 2011 15:10 »
Did you remove the mag and then refit it? If so, you might have retimed on the wrong cylinder.

You haven't stated which year and model (for shame!), so we don't know if the mag is manually controlled or automatically. If auto advance, did you time it with the advance mechanism wedged fully forward?

David
David
'57 Spitfire


Offline Duncan R

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Re: Pushrod question - problems starting new engine
« Reply #11 on: 12.02. 2011 17:50 »
Hi David,

Its an auto mag and the weights were wedged open before the pinion was put back on. I timed it on the timing side cylinder as per the BSA manual, As for the model - gawd knows what it is! Going by the frame number it was born a 1954 shooting star, once the engine was stripped it was discovered it was a 650 with Alloy head,thick flanged cylinders, std cam and Indian car pistons. At sometime in it's life it had a catostophic engine failure, the cases had been welded up and also one of the conrods had been welded back together and the crank could not be identified.I had the mag rebuilt a good few years ago and it has always been a good starter It now has proper pistons at 7.25, new (SH)rods and reground s/h crank and all bearings have been replaced
Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Offline iansoady

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Re: Pushrod question - problems starting new engine
« Reply #12 on: 13.02. 2011 10:22 »
Duncan,

I once rebuilt an XT500 and managed to retime it 360 degrees out, ie on the exhaust stroke rather than compression. It was exactly like yours with an occasional cough and very occasional huge bang - I suspect because of a build up of mixture eventually being fired.

I would check and recheck that the cylinder you're checking on is on compression, and also that you're sure which plug lead is being supplied. ISTR that the points correspond to the slip ring, ie when the points are towards the front of the mag the spark is coming from the front plug lead (but I could have that wrong).
Ian.
1962 Golden Flash (arrived)
1955 Velo Viper/Venom (departed)
2004 Triumph Tiger 955i (staying)

Offline Duncan R

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Re: Pushrod question - problems starting new engine
« Reply #13 on: 13.02. 2011 10:45 »
Hi Ian,

Thanks, I will check that tomorrow (stuck at work today) Do you know which  lead supplies which cylinder? I thought it was front lead supplies timingside and rear lead driveside.

Thanks
Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100
BMW R80GS
BMW R1100GS

Offline iansoady

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Re: Pushrod question - problems starting new engine
« Reply #14 on: 13.02. 2011 10:52 »
It can be either way round as there's no fixed relationship between the mag and the crankshaft (as it depends on the relative position of the driving pinion). If you think about it, the mag turns for 180 degrees for every 360 of the crankshaft and so it's quite easy to get it wrong as I've found to my cost. It's hard to see which plug lead the mag is firing as you can't see the brass segment on the slip ring when it's all in situ.

The hardest I've done was a V8 LR Discovery which was a real pain.
Ian.
1962 Golden Flash (arrived)
1955 Velo Viper/Venom (departed)
2004 Triumph Tiger 955i (staying)