1962 Arrow Starting Problems

bh.sprint
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Re: 1962 Arrow Starting Problems

Postby bh.sprint » Wed Jun 12, 2019 8:36 pm

The compression does seem to be low but I've had a bike with similar compression after a re-ring and it started OK and the compression eventually increased to a normal level. ( on one engine I used Aspen fuel after a rebuild and it started more easily than normal )

The primary compression ( crankcase ) is not easy to check but it may be possible to feel air being drawn into the carb or if the carb is off into the inlet.

Is the bike using points or other ignition ? and is the carb clean especially the primary circuit ie pilot jet and the passages around it.

Has the frame been grit blasted and bits of grit got into the carb or engine ?

Brian H.

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Re: 1962 Arrow Starting Problems

Postby White.John.A » Wed Jun 12, 2019 11:05 pm

Hi Brian,
I’M not sure if your response is to Melvyn or me as our problems seem to be similar. In my case I have had the bike on the road. My problem is I have to push it home. I have used the higher grade of fuel but I don’t know what Aspen fuel is. I use a Myvac to check the sump, which holds its pressure and vacuum. I am using the original points system on my bike as I was unable to get the electronic system bought from Drags. to work.
I had hoped that I would be tidying up the bike by now, but I am still trying to get it to run properly. So any thoughts of grit blasting is still a future dream.
Thanks for your help, it’s nice to receive advice from people much more experienced than myself.
John

bh.sprint
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Re: 1962 Arrow Starting Problems

Postby bh.sprint » Thu Jun 13, 2019 8:39 pm

Hi John,

I was replying to the last post but also had in mind the earlier replies to you.
Aspen fuel is mainly used by gardeners it has a long shelf life and gives off far less fumes, I found it good to start the Arrow I only use occasionally but it is very expensive.

I like the pressure/vacuum tester you have seems like a good way to check the primary compression. I found mine was leaking by feeling the threaded hole in the crankcase front, there was a pulsing when the engine was running. Blocking the hole with a bolt cured it and made the engine a bit more lively.
The hole should be blocked by the cylinder spigot but it was still leaking.

The points system is OK provided the condensers are OK and it is not too worn, using remote condensers or even a Triumph back plate with points which can be adjusted individually is better.

I found my first Arrow engine would not start occasionally it turned out to be bits of rust from the double skin rear engine mount dropping into the carb and blocking the pilot jet. I used a fine filter over the carb inlet and dripped primer + waxoyl into the mounting to hold the rust pieces.

Brian H.

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Re: 1962 Arrow Starting Problems

Postby Ivor Collins » Thu Jun 13, 2019 9:41 pm

Hi John
I don’t think that I can offer anything more to the suggestions already made but I was interested in your Myvac.
I have been looking at the idea of pressure/vacuum testing of the crankcase for some time and using a similar tester but stumped on how to test each side independently when the two halves are connected at the intake manifold. How can you know that the centre seal is not leaking from one side to the other?
I have even tried providing a path for air leakage past the barrel spigots to the tapped holes behind the exhausts and measuring th pulses there without success, for both a static and running engine
Interested in your thoughts

Regards
Ivor

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Re: 1962 Arrow Starting Problems

Postby White.John.A » Thu Jun 13, 2019 10:37 pm

Hi Ivor,
I have spent quite a lot of time mulling over this point without success. I believe that it is quite easy to pinch the lip of the seals when joining the cranks together or distorting them when levering the shaft to get the 0.002” shaft run out and would not know until the bike is put together and run. At the moment I put the bottom half together and test them for leakage before I put the top half together and test each cylinder pressure. Not ideal, but until I can come up with a solution, that’s the best I can do.
Regards,
John

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Re: 1962 Arrow Starting Problems

Postby White.John.A » Thu Jun 13, 2019 10:56 pm

Hi Brian,
Thanks for all the info. I did have problems with starting the bike, but lately it has been better. My new problem is it breaking down. Which I haven’t solved yet. I will look into your idea with the improved points as I sometimes get to the point where I run out of things to try. I also like to keep my eyes out on my bike for things that have Happened to other members .
Regards,
John.

Ivor Collins
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Re: 1962 Arrow Starting Problems

Postby Ivor Collins » Fri Jun 14, 2019 7:46 am

Hello John and thank you for your reply.

I did send a message last night it it must have got lost somewhere so here goes again!

I assume you have made a blanking plate to fit in place of the barrels to do the vacuum test? If that is the case, the two halves of the crankcase are still connected together at the inlet tract and generating equal pressure to either side of the centre seal. Are you doing something crafty to separate them or do you have a twin carb engine??

I also have little idea if the pressures generated in the crankcase, maybe peaking at 10 or 15 psi does anyone think?

Regards
Ivor

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Re: 1962 Arrow Starting Problems

Postby White.John.A » Fri Jun 14, 2019 9:12 am

Hi Ivor,
Yes I have blanking plates to check the bottom end. I have not come up with a way to separate the two halves yet.All the tests do is to let me know that the bottom half is pressure tight. I did notice with the latest strip down that there is an oilway between the two halves. I can’t see the point of this as the oil is in the petrol so everything is oiled.
I have not tried to see if the sump peaks, so unable to help you with that.
Regards
John

bh.sprint
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Re: 1962 Arrow Starting Problems

Postby bh.sprint » Sat Jun 15, 2019 5:19 pm

Hi John,

Just been working on the Leader and a though occurred to be , if the bike has a points sysytem are the points shorting out against the cover or is one of the contact breaker heals tightening up on the brass spigot and slowly stopping working.
I've heard of the heal tightening before Terry had the problem on a hot day.

Something else to tick off the list

Brian H.

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Re: 1962 Arrow Starting Problems

Postby White.John.A » Sat Jun 15, 2019 10:43 pm

Hi Brian,
Good thoughts Brian. I’m sure I read on this site some time ago that some members had trouble with points shorting out on the cover. I leave the cover off when in the garage and for road use I have made a wooden spacer that fits under the metal cover. It just keeps the cover away from the points. I will keep my eyes out for the points jamming. I am now putting the bike back together even though the compression is low. My latest idea is to ride the bike until it breaks down. I will then check the points and flow of fuel. I’m Hopping this will tell me if it’s electrical, fuel or mechanical. Should have thought of this idea sooner.
Thanks for the tips. I try them all,and as you say tick them off.
Regards
John


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