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Re: squish too big = non runner? - ports heights
Posted: Mon Aug 30, 2010 10:24 am
by lambrettasam
Hi all,
here's the setup: stage IV 200 top end on standard jet200 engine. Mikuni TMX 30 carb. Varitronic ignition, JL2 exhaust.
After checking timing (stator set completely counter clokcwize); carb (tried with a PHBH28), another spark plug, checked piston if piston was not mounted wrong way (no) checked breather in fuel tank (breathes ok) engine still wouldn't start.
i checked squish last night. And what a surprise, i found i had more than 3,5 mm ! squish with the original 1,5 mm head gasket. So i took it off and recheck: actual squish is 2,2 mm.
Could this be the reason the engine doesn't starts? What should i do? I can't go go lower than 2,2 as i don't have a gasket? Could i try to use the original jet200 head?
Thanks,
S
a
m
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 11:14 am
by drunkmunkey6969
Are there any gaskets under the cylinder base? Does the cylinder head have a 'lip' or is it machined flat?
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 11:55 am
by lambrettasam
Hi drunkmunk,
here's a pic of my head. There's a little lip (can mesure tonight if this helps)
Uploaded with
ImageShack.us
I have a thin gasket between engine case and cylinder base. (0,5 mm i think)
Thanks,
S
a
m
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 11:59 am
by ArmandTanzarian
Recently a mate of mine stripped his TS1 after the head gasket blew. The squish was about 2mm or more! This was no home lash-up but the product of a well known dealer.
The thing is, up until the gasket went, it had given more than two years completely fault free running and had all the performance you would expect from a TS1.
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 12:02 pm
by rocho68
it should still "fire up " .... :bouncing:
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 1:09 pm
by lambrettasam
rocho68 wrote:it should still "fire up " .... :bouncing:
hmmmm
that's the reply i was afraid of. What could it be then? Knowing that before putting the stage IV on it ran.
What if i take the base gasket off? This will modify the diagrams no?
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 1:19 pm
by hungdog
lambrettasam wrote:Hi all,
here's the setup: stage IV 200 top end on standard jet200 engine. Mikuni TMX 30 carb. Varitronic ignition, JL2 exhaust.
After checking timing (stator set completely counter clokcwize); carb (tried with a PHBH28), another spark plug, checked piston if piston was not mounted wrong way (no) checked breather in fuel tank (breathes ok) engine still wouldn't start.
i checked squish last night. And what a surprise, i found i had more than 3,5 mm ! squish with the original 1,5 mm head gasket. So i took it off and recheck: actual squish is 2,2 mm.
Could this be the reason the engine doesn't starts? What should i do? I can't go go lower than 2,2 as i don't have a gasket? Could i try to use the original jet200 head?
Thanks,
S
a
m
Does it spark ?
woodruf key still in place ?
old fuel ?
air leak ?
Re: squish to big = non runner?
Posted: Mon Aug 30, 2010 1:46 pm
by lambrettasam
It sparks nice (checked the regulator and CDI and these are ok)
woodruff key in place
fresh fuel
air leak maybe between cylinder and head now i took off the gasket.
Someone mentioned lack of primary compression that's why i thought about the squish. I'll check piston and piston rings but the whole top end was never used before.
Re: squish too big = non runner?
Posted: Mon Aug 30, 2010 2:59 pm
by coaster
Is the fuel getting through, is the plug getting wet?
Also, you say the woodruff key is in place but have checked? they cab easily be pushed out when you fit the flywheel.
Re: squish too big = non runner?
Posted: Mon Aug 30, 2010 3:36 pm
by lambrettasam
yep fuel is going trough as i have a fast fuel tap and am able to start it using start pilot. Once it has started, it runs idle and even revvs. When i cut the engine, it will turn on the second kick (without start pilot). But after a minute or so, impossible to start again without the use of start pilot.
Double-checked woodruff key and it's still where it should be.
