Tiger Cub - Problem!

[maggar]

Before I explain this I should say that I am far from being a mechanic; I will service my bikes, changing oils and filters etc. and I'm happy to tinker with frames and suspension and the like but the hot oily bit in the middle and especially electrics has me bamboozled!

Right, the Hardy Cub I bought about 6 weeks ago I have only ever ridden on my land and it has always started first or second kick and has run perfectly. I was due to enter my first Pre 65 trial today at Sowerby Bridge so yesterday I fired her up and had a few minutes tight turning on the drive. After only about 3 or 4 minutes it seemed to cough a bit when I went to lift the front wheel, like it missed slightly then picked up. It did this twice then stalled. I kicked it over and it started but stalled again pretty much immediately. I went to kick it over again and found that the kickstart was very stiff and then with the next kick totally locked!

Thinking it had seized I swore loudly then removed the plug, which was very black, and tried to push the kickstart with my hand - it turned without resistance. Phew!

I thought it might be a problem with the plug so I changed it and tested that there was a spark - all good. Kicked it over and it started okay but died again quickly and once again the kickstart stiffened up. I did check when it was briefly running that oil was circulating through the flow and return pipes to the sump / tank and it was.

I have now repeated this a few times and each time the same result; the bike will kick without a plug in but with the plug in the kickstart stiffens after one rotation. I have not attempted to kick it into life again for fear of serious damage.

This is the bike I showed in a previous thread (Fred Hardy Cub), it has pvl ignition.

I'm very worried that it's something serious, I have quite a lot of money in this bike and really want it to be right.

Maybe she just didn't fancy getting dirty!

Any thoughts?

[alan]

The kick start problem sounds more like a gearbox issue than an engine problem.

Wear in the gearbox bushes and the sleeve gear bearing can cause the gears not to mesh properly.

Have you tried Kicking it over with the clutch pulled in, when the kickstart goes tight ?

I suspect that when you have the plug in, the extra load on the main shaft pulls it out of line. removing the plug takes the load off.

Pulling the clutch would have the same effect.

The main shaft passes through a bush in the sleeve gear, the sleeve gear is then located in a bearing in the gearbox housing. The sprocket is then splined onto the sleeve gear. As mud gets packed into this area, and is often pressure washed out,it is quite common for both the bush and bearing to be badly worn.

If your crank cases have been cut away, you may be able to see movement in the sprocket by pulling on the chain with the bike in gear.

To check for play in the sleeve gear bearing and bush, you really need to remove the clutch plates and get hold on the clutch centre and check for play.

Edited March 2, 2015 by alan

[totalshell]

frankly you should be celebrating..the weather was the worst i ve ever trialled in.. sleet hail gusting winds.. proper hard man stuff but 50 or more middle aged blokes braved it on everything from rigid ambassadors to show queen ariels. nice compact trial no mud some climbs and some sections had no rocks or stones..

[maggar]

I'd still rather have been there than fretting about the cub at home!

Alan, thanks for that.

I have just tried to kick it with the clutch in and the kickstart does go loose. It doesn't feel the same as the normal kickstart stroke but it is loose.

It sounds as though you are right although there doesn't appear to be much if any play in the drive sprocket from a cursory look.

What scale of job am I looking at bearing in mind that it sounds beyond my rudimentary skills so I'll be paying for it to be done.

I paid good money for the bike only two months ago so I'm a bit hacked off to say the least but I suppose this could have happened at any time?

Edited March 2, 2015 by maggar

[old trials fanatic]

Please take this the right way because that is how it is intended. I have had a friend with a problem with a Twinshock he recently bought and he has only rudimentary mechanical skills and aptitude. He really liked the idea of Twinshocks and loved the look of a Bultaco. you know the thing all shiny pristine paint blah blah blah. Well he has just sold it and gone and bought a 2010 Gas Gas. Why? Well he had what i thought were a couple of niggling problems that could have been sorted but the main problem couldnt and never would be sorted. What was it ? As i said he had only rudimentary mechanical skills like change oils, filters a plug etc. He couldnt even come to terms with having to strip the wheels out after each trial and clean the brake shoes. When i told him he had caused most of the problems, the bike was fine when he bought it btw, by pressure washing the bike he looked dumbfounded.

So whats the moral of this diatribe ? If you want to run a Twinshock you NEED more than a rudimentary knowledge of mechanics and should be prepared to strip an engine and replace crankshaft oil seals bearings etc. If you want to run a Pre 65 then learn to become an engineer as they require a LOT more maintenance and prep than Twinshocks. Just about ALL Pre 65 bikes running nowadays are really one off prototypes. the phrase "I paid good money for the bike" is irrelevant. In a VERY short period of time, OK perhaps not as soon as the problem with yours, it would be requiring maintenance and i dont mean oil and filter changes. Remember they needed quite a lot, by modern standards , of maintenance in the day and nothing has changed.

I am not trying to be derogatory please believe me just trying to offer some advice to prospective purchasers of Twinshocks and definitely Pre65 . i constantly depresses me how little people know nowadays of simple maintenance procedures like stripping an engine and seem to think what is basically a 60 year old design should be like a 10 year old one.

Perhaps if this is the case might be best to cut your losses and buy a modern that you can just change oil and filters on wash and put away till the next ride ? I hope i havent offended because that was NOT my intention just an observation.

[japes1275]

Before you start pulling it apart you should make sure there is something wrong internally or at least try and diagnose where the problem lies.

With the clutch disengaged (lever pulled in) you have in effect disconnected the kickstart/gearbox from the engine. All you are doing is rotating the gearbox using the clutch ratchet. If it's doing that smoothly then I would say the chances are that the kick start and gearbox are ok.

If you then take the spark plug out and kick it over with the clutch engaged (lever out) and it kicks over fine then I would definitely say all is is well in the kickstart/gearbox/clutch. (Baring a major breakdown in a bearing or sleeve gear which I would say you would still notice)

While the plug is out then check that when you kick it over that the piston rises and falls smoothly and that it feels free. If not and it still takes a bit of effort (you should be able to turn it easily by hand on the kick start) then it may have seized. Bear in mind that if the engine is newly rebuilt then it may be a bit tight on the bore till run in.

If all seems well then I would start looking at things like ignition timing as that can easily give the symptoms you mention.

The last time I stripped my B40 down for something I wasn't sure about I really regretted it as I hadnt a clue what was wrong and only found out what it was by chance as I was reluctantly rebuilding it. Obviously it might not be possible to find out what is wrong without stripping it but it's a good idea to check as much as you can first.

Let us know how you get on!

[japes1275]

Just remembered this, when I rebuilt my B40 (rebored) it was really tight to start with. It would start fine when cold but if you needed to start it hot it was difficult and would not always kick over. With the type of clutch/gearbox on your bike if the engine is tight or right on compression sometimes the clutch slips as you are trying to kick it over. This could be what is happening but you are interpreting it as something wrong as the engine isn't turning over.

Although your bike is a fully modified trials bike getting hold of the basic owners manual for the Cub would be a good idea if you've not already got one. It will cover all the basics and some manuals from back then covered the theory of operation as well.

[old trials fanatic]

OK assuming you havent taken offence. I suppose you have checked the obvious that the correct length plug is in it ? Yeah obviously sorry too simple. I'll get me coat.

[maggar]

Thanks Japes.

The kickstart does turn easily with the plug out by hand and all feels "right" with the mechanism if you know what I mean.

Also if it was just an issue with the kickstart gear this wouldn't explain the pop - fart - die, which is more likely to be timing / ignition related. I will check this prior to pulling it apart; a mate who is a very experienced bike mechanic is going to give me a hand on Wednesday.

Thank you.

OTF - no offence taken at all. I may be (slightly) underplaying my abilities but not by much!

I have 5 trials bikes including the Cub, two 1980 Fantic 200's one of which I am in the process of restoring (its little two stroke engine is in pieces on my work bench at the moment) a 1986 Fantic 201 and a Fantic 303 which I bought already restored but which has since needed a lot of sorting out. I have no interest whatsoever in modern trials or modern trials bikes and have no intention of training as an engineer; I seriously doubt that every owner of Pre 65 trials bikes is so qualified although I accept that many will be.

I do understand that Pre 65 bikes will require more in depth maintenance than an oil and filter change every now and then and I will, as I have done with my other bikes gradually learn what I need to. Where I run out of talent I will try to get advice from this excellent forum, the many friendly and helpful trials riders I've met and my excellent friends nearby.

You shouldn't get depressed about how little people know nowadays but be cheered by how much some of us want to learn, and be downright chuffed to bits that we actually want to ride and compete on these lovely old machines.

I'm genuinely grateful for ALL responses especially to those like yourself who take the time to explain procedures and possible solutions to those of us with less knowledge, it is appreciated.

Edited March 3, 2015 by maggar

[maggar]

Just remembered this, when I rebuilt my B40 (rebored) it was really tight to start with. It would start fine when cold but if you needed to start it hot it was difficult and would not always kick over. With the type of clutch/gearbox on your bike if the engine is tight or right on compression sometimes the clutch slips as you are trying to kick it over. This could be what is happening but you are interpreting it as something wrong as the engine isn't turning over.

Although your bike is a fully modified trials bike getting hold of the basic owners manual for the Cub would be a good idea if you've not already got one. It will cover all the basics and some manuals from back then covered the theory of operation as well.

I have a copy of the original workshop manual as well as the Haynes one. I also have Fred Hardy's original hand written notes on what he did do the internals when he built it.

The engine on my Cub has not ist been rebuilt and it has been running and starting perfectly (admittedly probably for only an hour or so in total) up to now.

If I remove the spark plug and turn the engine over and then replace the spark plug I can kick it over once and it may or may not start. If it does start it stalls after a few seconds, if it doesn't start the second kick will produce a rigid kickstart. Bizarre!

Edited March 2, 2015 by maggar

[japes1275]

What happens if you leave it a few seconds/minutes after its stalled and the won't turn over? Will it then turn over ok and start?

From what you are describing with it popping and running a few seconds it sounds like an ignition issue, possibly timing. You could start by trying the most obvious and cheapest with a new or different plug, then maybe checking the actual timing. Not sure how that's done on a Cub but probably the old measurement of piston height. Maybe it's been set up for timing with a timing light though.

Also a check of other obvious things like fuel blockage, crap/water in carb float and fresh fuel just to eliminate them.

Edited March 2, 2015 by japes1275

[b40rt]

Kick start gears not meshing ?

[maggar]

No, if left for a few minutes or even hours the kickstart is still rigid. Only removal of the plug releases it.

Tried a new plug straight away on Saturday, didn't make any difference.

Going to check ignition with the help of a suitably clued up mate on Wednesday night.

I think (but need to check) that the kickstart gears do mesh because it will occasionally start with the single kick you can give it before the kickstart seizes up, also the kick "feels right" and is exactly as it has been when it started and ran fine before Saturday.

I will check all the other things you mention too.

Thanks.

Edited March 3, 2015 by maggar

[trialsrfun]

There is a pawl mechanism in the kick-start which if worn would not engage in properly, this is why when starting a Cub it should be turned over compression then let the kick start back up then press smoothly down to start each and every time stabbing at it will certainly ruin the pawl mechanism.

Also as OTF says pressure washing (almost anything) is a big no no, the best place for a pressure washer is on ebay unless you are washing moss off concrete.

[maggar]

I am extremely careful when cleaning my bikes and have never used a pressure washer on the Cub as this bike has only been ridden around my drive and has not been dirty yet under my ownership. My other bikes are washed off with garden hose, soapy water and elbow grease!

The kick start is engaging properly I'm sure but I agree about "stabbing at kick starts" on any bike.

Thanks.