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  #61  
Old 16th July 2018, 04:56 PM
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Gixxer Gixxer is offline
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Default Re: Can I build a kit bike?

Originally Posted by pedrosixfour
Thicker head gasket perhaps?
That would fuck up the valve timing. You'd have to fit vernier cam sprockets to fix it.

Last edited by Gixxer; 16th July 2018 at 04:57 PM.
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  #62  
Old 16th July 2018, 05:57 PM
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Biker.ie Member No. 36909 from Laois/Offaly
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Default Re: Can I build a kit bike?

Originally Posted by Gixxer
That would fuck up the valve timing. You'd have to fit vernier cam sprockets to fix it.
Originally Posted by RTV
Does that mean that you're game for the upgrade?
The man has it already figured out in his head, sure he'd have it done while you're making the tay!
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  #63  
Old 16th July 2018, 10:40 PM
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Default Re: Can I build a kit bike?

Originally Posted by RTV View Post
1) Do whatever the fuck you want.

2) I would have to partially agree with the haters by saying that you should start with small projects, if you can, maybe try to get a functional bike with maybe some minor issues to fix. You can start playing and work your way around the simpler jobs like regular service, change brake fluids, pads, oil, filters, sparkplugs, things like that that should be simple enough. As you progress you'll see if it's for you or not.

3) When rebuilding a bike you'll find yourself in cases where you'll either have to invest in specialist tools or go to a shop to get it done. So you're either ready to put money on tools or outsource work, either will cost you additional money so have that in mind.

4) Do whatever the fuck you want.
Solid advice there. Much appreciated.
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  #64  
Old 17th July 2018, 12:10 PM
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Default Re: Can I build a kit bike?

Originally Posted by Gixxer
That would fuck up the valve timing. You'd have to fit vernier cam sprockets to fix it.
The thicker gasket/spacer allows a larger space in the combustion chamber for the extra fuel/air mix from the turbo. How would vernier cam sprockets achieve the same?
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  #65  
Old 17th July 2018, 12:17 PM
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Default Re: Can I build a kit bike?

Originally Posted by renniks View Post
The thicker gasket/spacer allows a larger space in the combustion chamber for the extra fuel/air mix from the turbo. How would vernier cam sprockets achieve the same?
No, the vernier sprockets would be needed to return the valve timing to the correct value in relation to piston position.

Increasing block/head height effectively shortens the timing chain meaning the camshaft timing would be retarded (valve events happening too late) than it should be for optimum efficiency.

Last edited by pedrosixfour; 17th July 2018 at 12:19 PM.
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  #66  
Old 17th July 2018, 12:41 PM
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Default Re: Can I build a kit bike?

Originally Posted by renniks
The thicker gasket/spacer allows a larger space in the combustion chamber for the extra fuel/air mix from the turbo. How would vernier cam sprockets achieve the same?
They wouldn't. They'd allow you to fix the cam timing after fucking it up with a thicker head gasket.
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  #67  
Old 17th July 2018, 12:45 PM
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Default Re: Can I build a kit bike?

Originally Posted by pedrosixfour View Post
No, the vernier sprockets would be needed to return the valve timing to the correct value in relation to piston position.

Increasing block/head height effectively shortens the timing chain meaning the camshaft timing would be retarded (valve events happening too late) than it should be for optimum efficiency.
The cam timing would advance with a thicker gasket.
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  #68  
Old 17th July 2018, 12:53 PM
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Default Re: Can I build a kit bike?

Originally Posted by pedrosixfour View Post
Increasing block/head height effectively shortens the timing chain meaning the camshaft timing would be retarded (valve events happening too late) than it should be for optimum efficiency.
That makes sense alright!
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  #69  
Old 17th July 2018, 01:04 PM
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Default Re: Can I build a kit bike?

Originally Posted by Gixxer
The cam timing would advance with a thicker gasket.
Damn auto-correct!

I really need things things in front of me to get to grips with them, it'd all make sense then!

Last edited by pedrosixfour; 17th July 2018 at 01:09 PM.
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  #70  
Old 17th July 2018, 01:07 PM
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Default Re: Can I build a kit bike?

I'd be of the opinion that you should buy a doer upper. See if you can get hold of a 250 2 stroke and be amazed at the fun that can be had with small smokers :)
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  #71  
Old 17th July 2018, 01:31 PM
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Default Re: Can I build a kit bike?

The tensioners would usually allow for the changes in cam chain length, you're not talking miles.

I have seen thicker head gaskets used to lower compression as well as shims being used with two head gaskets. It does work but it's a bodge.
It fucks with the squish area and makes for hot spots and det.
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  #72  
Old 17th July 2018, 01:46 PM
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Default Re: Can I build a kit bike?

Originally Posted by Frisco View Post
The tensioners would usually allow for the changes in cam chain length, you're not talking miles.
The tensioner is on the slack side of the chain. It has nothing whatsoever to do with cam timing.
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  #73  
Old 17th July 2018, 02:28 PM
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Default Re: Can I build a kit bike?

It works, I've seen it done and cam timing wasn't an issue. There are other issues though
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  #74  
Old 17th July 2018, 04:17 PM
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Default Re: Can I build a kit bike?

Originally Posted by Frisco
It works, I've seen it done and cam timing wasn't an issue. There are other issues though
What do you mean by 'it works'?
I've turbocharged quite a few engines. The last one I did was an 1127 oil boiler, and the cam timing needed retarding by over 3 degrees. That's a very significant amount, and definitely what I'd call 'an issue'.
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  #75  
Old 17th July 2018, 04:56 PM
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Default Re: Can I build a kit bike?

You lowered compression by using thicker head gaskets or a decompression shim and retarded the cam to compensate?

When I say it worked I mean that a thicker MLS gasket was fitted to lower compression and when the cam (an aftermarket one) was dialled in on standard marks the timing wasn't out enough to warrant fitting verniers.

The bigger issue was the squish area being fucked because of it
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  #76  
Old 17th July 2018, 05:53 PM
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Default Re: Can I build a kit bike?

Originally Posted by Frisco
You lowered compression by using thicker head gaskets or a decompression shim and retarded the cam to compensate?

When I say it worked I mean that a thicker MLS gasket was fitted to lower compression and when the cam (an aftermarket one) was dialled in on standard marks the timing wasn't out enough to warrant fitting verniers.

The bigger issue was the squish area being fucked because of it
The scenario I'm talking about is a thicker head gasket, because that's what we're talking about.

What was the original CR of your turbocharged engine? And what was the finished CR? How much thicker was the gasket than stock? What diameter was the timing pulley/sprocket? What engine was it? How much did the timing advance?

All these questions and more, because...

"the timing wasn't out enough to warrant fitting verniers"
isn't a recognised measurement, or one that I can work with or understand
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