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 Post subject: Top end spruce up
PostPosted: Tue Sep 20, 2016 10:41 pm 
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Location: derbyshire
Got a few miles on the X1 now probably 40-50K ( not exactly sure due to overpriced speedo sensors) and the base gasket weep is showing signs of development.
So I am going to venture in this winter.
I am interested in knowing the best way to get a working squish band clearance with the miss matched piston and head squish angle Pash spoke of and also in knowing what is likely to need refreshing.
The bike uses some oil but no more than it always has. I have always changed the oil around 2- 2 1/2K miles. When I fitted the Lucky hands gear a couple of years ago ( probably 6K ago) The old gear looked virtually as new. It still feels strong on the road and produces just shy of 90hp on the dyno and it doesn't seem to be visually smoking at all although it must be to some extent.

I am generally really happy with the bike and would leave well alone if it wasn't for the base gaskets.

I am not looking to throw a load of money at it to gain a couple of HP but i am looking to get it running well and lasting well before further work is needed. I know from building 2 strokes that having the correct squish clearance results in a sweet running motor so it seems wrong to ignore it whilst the engine is apart.

I suppose a compression test would be a good start, what figures should I be looking for?
I presume new gaskets and seals. What else is likely to be worth doing now rather than later re valve guides, seats, rings etc.

I will measure things when stripped but what are your findings? Cheers.


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 Post subject: Re: Top end spruce up
PostPosted: Wed Sep 21, 2016 1:03 am 
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If you're blowing speedo sensors you need to rewire the feed to it. Info about that is here somewhere.

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 Post subject: Re: Top end spruce up
PostPosted: Wed Sep 21, 2016 5:50 am 
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The squish band on the Thunderstorm heads is cast and it is 15 degrees whereas the dome on the piston is 10 degrees. To get the squish right, you will need to skim the head, well in excess of 1mm, then recut the squish band at the correct angle.

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 Post subject: Re: Top end spruce up
PostPosted: Wed Sep 21, 2016 11:32 am 
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TBH, if you're expecting to find much more power, I think you're limited by already having ~90 rwhp. With a stock motor I doubt you can't expect to find much more, I think. You need after market valve stem seals, they'll be leaking. But if not already done, the speedo sensor feed needs modifying.

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 Post subject: Re: Top end spruce up
PostPosted: Wed Sep 21, 2016 11:36 am 
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pash wrote:
The squish band on the Thunderstorm heads is cast and it is 15 degrees whereas the dome on the piston is 10 degrees. To get the squish right, you will need to skim the head, well in excess of 1mm, then recut the squish band at the correct angle.

...........and cc the chambers back to stock.

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 Post subject: Re: Top end spruce up
PostPosted: Wed Sep 21, 2016 1:55 pm 
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proff. patpending
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03 wrote:
pash wrote:
The squish band on the Thunderstorm heads is cast and it is 15 degrees whereas the dome on the piston is 10 degrees. To get the squish right, you will need to skim the head, well in excess of 1mm, then recut the squish band at the correct angle.

...........and cc the chambers back to stock.

I don't think I would, the compression ratio is pretty low as stock to accommodate low octane number fuels and the lazy squish band. Knock sensitivity increases with large throttle openings at low speeds, and if you get problems you can retard the ignition top left in the map. Far easier to deal with than the VOES on the carbed models.

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 12:09 am 
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Stock CR is around 10.5:1 and it's easy enough to provoke pinking anyway. How high should you make the CR and how many CC's would the resulting chamber be?

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 1:58 am 
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I'd like to get in on this if I can , I've got stock heads on mine and it makes a baw hair under 95 rwhp, it's got a minor leak from the rear base gasket so I'm planning to replace them soon, I'll have to go over all your posts in the how to section nick :yup:
it'll be interesting to see what difference it makes

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 2:04 am 
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Speedo sensor needs to have its feed taken from the cam position sensor.

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 5:44 am 
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proff. patpending
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03 wrote:
Stock CR is around 10.5:1 and it's easy enough to provoke pinking anyway. How high should you make the CR and how many CC's would the resulting chamber be?

You can work it out based on reduction in deck height v's the 'stock' CR, but I'll bring you back to the point regarding limitations of VOES and poorly formed squish band.

gusm2 wrote:
I'd like to get in on this if I can , I've got stock heads on mine and it makes a baw hair under 95 rwhp, it's got a minor leak from the rear base gasket so I'm planning to replace them soon, I'll have to go over all your posts in the how to section nick :yup:
it'll be interesting to see what difference it makes

95 is very good for a stock engine.

gusm2 wrote:
Speedo sensor needs to have its feed taken from the cam position sensor.

Why?

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 8:15 am 
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It's only 5V and won't blow it.
Maz did a kit a while back.

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 9:26 am 
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proff. patpending
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Sorry, thought you were talking trigger pulses. Yeah 5V is cool.

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 9:28 pm 
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Yes thanks for the input. This is what I thought from reading around.
There is some benefit from just decking the head and staying with the miss matched cast squish. How much I am not sure.
Machining the deck enough to allow machining of the squish will be better, but a lot more complex and expensive. Plus the added problems or benefits of higher compression. Not sure I want to start experimenting that far. Can't afford to break it.
It is a shame about the miss matched angles between head and piston, It turns a simple job into something that puts me off getting involved.
Money no object then XB parts have a better start to work from it seems But it is an object.

Probably just try and get the cast squish at a working clearance as a compromise. I am not after outright performance just sweetening what I have got by improving efficiency.


Has anyone done this> is it worth it?
Maybe just gaskets seals, de-coke and valve seats lapped is all that is worth doing ?

I don't want to loose reliability. Too much tuning will just encourage abuse. Not a good idea.


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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 9:51 pm 
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Quote:
Maybe just gaskets seals, de-coke and valve seats lapped is all that is worth doing ?


:yt: IME :)

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 Post subject: Re: Top end spruce up
PostPosted: Thu Sep 22, 2016 10:25 pm 
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Location: derbyshire
I have seen online posts from reputable? engine builders omitting base gaskets and using 3 bond instead to reduce squish clearance. Is this suitable for a road machine or will I be doing the job again before anything else wears out?


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