OK PROBLEM STILL THERE HOW TO SET TIMING AND JET SIZES

[runutz698]

Hey Guys I replaced the seals the fly wheel side was crappy so I was hoping that was going to be the problem.

So thus far I have
a.) taken barrel off honed new base gasket and laped the head in

b.) Replaced crank seals and gaskets.

c.) Change heat rating on the plug to cooler

d.) Covered the motor with water whilst running(hopping it would either suck or blow the water) with no leaks present on any obious parts

The bike starts first kick everytime, I had up against a brick wall before starting it so I could stall it as I was ready for it this time. Whilst sitting there idiling the engine does pick up rpm as it gets warmer but this takes a few min. So I am know thinking

a.) What size jets should be in the carby

b.) What the timing should be set to and how to set it as there seems to be no marks

c.) What is the correct plug for the bike

When starting it feels like it has a bit of kick back like the timming is advanced to far so was going to try retarding it a fraction and see if any improve.

What are your ideas guys as this really starting to give me the sh#$'s,

As it is an unkown thing, I am willing to try anything lol,

But If it is an air leak it is must be so small(as I can't find anything) and for it suck that much air in the short time I have had it running(I am talking minutes max time it has run would be 3min and that was in the first take the hell razor) to lean out that much sort of seems a bit wierd if it is a small leak as I have a had a bike with a leaking crank seal and it didn't do this and was still ridable(but a bitch to start).

Your imput would be great,

Also how do you time these guys and what should the timming be Mr.Jared??"

TOm

[414VG]

Make sure the exhaust pipe isnt leaking where it mates onto the cylinder barrel.  What model of cappra is it?, If its got electronic ignition, the timing hole on flywheel should line up with the timing hole on stator when the motor is 3mm from TDC.

Sandy.

[runutz698]

It is a Capra VF250 with a motoplat ign. So does the whole thing still apply, I imagine it would

Cheers
Tom

[414VG]

should do, Jared will confirm but i am sure its 3mm BTDC on my 414vg's..

[cappra]

Correct.  All mxer's have the timing set at 3mm BTDC.
Your going to have to use a dial indicator.  The indicator
screws into the plug hole and you rotate the motor until
the piston comes up to top dead centre and reverse direction
until the indicator shows 3mm before top dead centre.
At this point, the hole in flywheel should line up with the
hole in the stator.  If not, loosen stator plate screws and
adjust accordingly.  A small length of welding rod works
well as a locator pin.

[runutz698]

Ok cheers guys,
that seems straight forward,

now what size jets should be in the carby just wanting to make sure somoeone hasn't rebuilt it with the wrong size jets. And what is the standard NGK plug I should be running.

DO you guys still think it sounds like an air leak??

Cheer
Tom

[cappra]

Not 100% sure if the VF250 jetting is the same as VE250,
as I don't have a VF250 manual.  Here is the stock VE 250 jetting.
main jet-175
pilot jet-50
needle jet-2.84
needle-8G3
NGK B8ES for a plug.
Keep thinking there is a problem with the carb. 

[paul]

dr ross  do you still do house calls

[runutz698]

Dr.Ross sorry to disapoint that has already been replaced,

The mech reckons it is cause it is from a deceased estate.....

Nothing is making sence at this stage so. I am going to got he carby option at this stage check it from top to bottom.
This is one big learning curve I can tell you...

Cheers Guys Keep thinking, I don't have any ideas really I am just clutching at straws at the moment.

[runutz698]

Just thinking out loud is anyone here Based in melbourne(Iam based in Bayswater) and have a carby I could borrow just to rule the carb out??

Cheer
Tom

[runutz698]

Hey Guys, I can't stop thinking about this
Also Just another thought if the ignition was to far advance how long do you think it would take for it to heat the plug to make it run on?? I mean a minute or so??

If it heated up it means that once you open the gas and close it would then be fuel starved so it would act like it is running out of juice and speed up as a 2-stroke does and while there is that small amount of fuel coming in it would keep running.

Tom

[runutz698]

Hey Guys it was the big end getting hot and also causing very high comp under revs, It looked ok when inspected before starting the bike and it was tight and felt ok,
however once running it must of been a broken roller in the cage as the conrod looks to of been heated up with an oxy torch now. While the crank and everything around it was all covered in oil and fuel the big end was dry, I think that it was getting hot causing the piston to rise higher in the bore and in turn increasing the comp and making it disiel.

So we checked and o-ringed the whole carby, replaced the carby conector again. But it still did it. so we got creative and thought the comp may be to high so we spaced and the barrel with 2 base gaskets and it ran fine reved idled reved idled,  truned off how it should. how ever after 5min it started to make and noise and threw the bottom end (not completley). So the problem  looks to of turned out to be a compresion problem as it was strectching the conrod under revs through heat hence it idled fine but as soon as you touched the gas it streched the conrod and then ran under it's own steem. The carb was set to run really ritch to stop it leaning out, so all I can say is wow no one could of guessed that.

So that is what we belive happened as it is the only thing that makes sence, A guy who is is an air craft mech, said in the air world they have to de bur every part to a polished surface once they machine a head or black as the bur's can hold enough heat to keep the motor running aswell which I found intresting.

[runutz698]

Jared it is poss. that the bottom end gave way when it reved to the moon.
 but the only thing that doesn't make sence is we striped it down yesterday to put the extra base gaskets in at that point we checked the bottom end and it was tight, The next thing is that even with the extra base gaskets it would run under it's own steem but if you gave it a rev it would clear it's self and turn off using the button if not it would just creeping up in revs from idle and the button did nothing. The next thing as of lastnight I split the motor with the mech after work and the crank looks abit suspect to, There are to marks on the bottom off the weights that look as though they should line up to balance the crank and make it run true so I am going to get it put on V blocks and see if my suspesion is correct and that it is out.

We are still kind of in the dark so we are going the rebuild so we know it is all good checking every part as we put it back togeather.

Can anyone measure the head for me and barrel as I am wanting to make sure somone hasn't shaved to much off each to rule out a compression issue which I highly doubt it but need to check.

So I need the full height of the barrel and also the step in the head!!!

Cheers
TOm

And ross there are 3 of us this end that are all dumb founded as every theory we run with does and doesn't make scence. I am hoping it is the crank out of kilter and that it the air leak, the only reason it got better with the base gasket was less preasure on the bottom end???

[cappra]

It would be very difficult to shave any material off of the cylinder,
as you would remove the sealing rings cut into the top of the liner.
You should be able to see if the head has been milled and I have seen
over 25thou cut off of the head without seeing any of the problems
you have run in to.  When together, the piston top should just come
up to the top level of the liner, anymore and it would make contact
with the head.  The aftermarket Wiseco piston makes me wonder
what's going on inside there!  If the pin height is not the same as
the oem Montesa piston or overal piston heighth is different, that
could cause numerous problems.

[runutz698]

Jared I forgot to tell the piston I have is a Mahle or how ever you spell it. I am going to track down a new piston through my local supplier's maybe as my old man got pistons made from all diffrent old cars and bikes from Zundapp's to triumph's to some greave's motors so I will go down that path first then if no sucess I will go to solo montesa and get it off him.

If any body know's where a .25thou piston for a 250 capra lies in the local markets please let me know....

Cheers
Tom