Bultaco compression issues

[steve234]

A week out from the astro's first run at Double the Dirt and she's got problems.

No compression! and the kick starter gear/ratchet is buggered.  :'(

The head has had the decompression release plugged by the previous owner which may be the cause? But they plugged it with a nicely machined alloy bung. If it was that i would have thought you could hear the air escaping but i can't make it out.

Any help would be greatly appreciated.

Cheers,
Steve

[Mark Austin]

The easiest way to check it to use a compression tester or just take the head off and have a look at the bore. That should tell you if there is anything sinister going on.
Cheers,
Mark

[runutz698]

Should of Just brought a montesa, I know where there is a nice 414 for sale ;-)

[steve234]

Runutz,

If you are offering it to me it must be a lemon  !  My checkered history of buying duds continues ha ha.

Mark,

I have had the top off and all looks pretty good. It's had a rebore to 2nd over. Seemed to be running ok after that for half a tank then nothing. Have new base gaskets in the mail but the one on it seems ok. Maybe the problem is the head sitting on the barrel? There was a smidge of oil on top of the cylinder when i first inspected but it was running then.

[runutz698]

Is the head laped in like the montesa's??

Cheers
Nuts

[steve234]

Nutz, lapped as in recessed ie. male to female? If so yes.

[runutz698]

If you think it is a head leak clean one side and put a smear of oil on the other, then clamp it down upon removal you will see which edges did not touch i.e. where the leak may be.

Cheers
Nutz

[holeshot buddy]

or make a very thin brass or copper circular head gasket and try it

[Moto]

Steve,
        Have you removed the barrel, and seen the piston to check that the rings are free and not stuck in the ring grooves. It may have lightly seized and stuck the rings last time you rode it.
        I have pulled heaps of these engines apart and have never found a kickstart ratchet stuffed.When putting an engine back together the ratchet needs to be in the right position and the return spring also.Unfortunately to check all this you need to split the cases.Was the engine rebuilt? by whom when you bought it.
        Back to your original problem, the lack of compression could also have the same feel when kicking it if the clutch is slipping.
        Just a few thoughts.

[steve234]

Think you have nailed it with the clutch slip moto.

It just didn't seem right "no compression that is" as nothing was really out of place so to speak. So i just did a little check whilst the head and cylinder were still on (I had previously checked the rings etc) selecting an appropriate gear and spinning the rear wheel gently whilst observing the piston through the pipe port. At first the piston operated as it should then stopped moving as the wheel spun with less resistance.

I'll adjust the clutch tomorrow and see how it goes.

Thanks for the help guys.

Cheers,
Steve

[steve234]

Well i am a shattered man!

Been 2 years in waiting to have a go at Nudgee dirt track as it was set up on the weekend. Yeah you guessed it, clutch slip thing popped up again. Even Don Newell couldn't work out what was going on (thanks for helping anyways) so i'll have to take it apart and start fresh.

Arrived late thanks to the misses stuffing about, as a result didn't get the DR scrutinised so didn't get to ride at all.

Got to watch a few laps though and it looked sweet. The day was really well run and all the guys got plenty of rides. Even saw another #106 astro having a go.

Better get the shed time issue sorted and get my shit together and start riding club days.

[Moto]

 Steve,
          Best thing to do with the clutch while it is apart is install Barnett kevlar clutch plates and springs.The original steel plates can be a real hassle if not in good condition and set up properly.Barnetts will stop the slipping and they are fairly inexpensive.

[steve234]

Cheers Moto, will do.

[steve234]

Sometimes ya just feel like a real twit!

Turns out the nut on the primary crank sprocket was loose.

AAArrrrrrgggggghhhhhh!!!!!!!!!

[Moto]

Steve,
       There is also a woodruf key that locates it on the crankshaft.make sure it is not sheared off because the nut has come loose.Clean the threads and locktite the nut on.There is also supposed to be a locking nut that locks to the main nut.