878 kit

idl1975 · Post by **idl1975** » Thu Nov 27, 2008 9:55 am

Tigcraft TRX wrote:Richard Albans (TTS) stated that the 878 pistons are 10.5-1 because the valve pockets are slightly deeper, but squish is improved through piston design. I told you that JE pistons were loads heavier Steve!! (joke)
I had to file a couple of the rings from my TTS kit slightly wider. TTS also don't bore the barrel as far as JE recommend, as JE produce predominantly car pistons, with clearances on the fitting instructions for V8's instead for bikes..
Make sure your gasket's bored as well.. The race is on for 878 rebuild - should get my engine back built mid next week. Tigcraft TRX is here!!!!!!!!!!!! (>100hp I hope)

I hope we're going to see some youtube videos?

HansJ · Post by **HansJ** » Thu Nov 27, 2008 10:36 am

Tigcraft TRX wrote:Richard Albans (TTS) stated that the 878 pistons are 10.5-1 because the valve pockets are slightly deeper, but squish is improved through piston design...

Interesting, but it doesn't sound right in my ears. (I am not killing the messenger here!). Of course the valvepockets are deeper, because there's more material on top of the JE pistons due to the dome. And how would the squish be improved, unless there's more material on the perimeter of the piston area, which also would mean higher compression (but from what I can remember, there was no difference when I measured?)

Bollox or not, but it would be interesting to know the real figure. Everywhere I have seen the 11,5 nr, but this can of course also be false.

steve speed · Post by **steve speed** » Thu Nov 27, 2008 12:45 pm

once mine are fitted i will do a pressure check and report back,,, we have the std numbers for psi so if there's more compression that number should be higher ,,perhaps others could do the same

steve speed · Post by **steve speed** » Thu Nov 27, 2008 3:06 pm

how did you lot get the pistons in the bore i am struggling a bit

HansJ · Post by **HansJ** » Thu Nov 27, 2008 4:23 pm

Keep struggling, "a bit" is not enough...

But be careful, it's easy to break the rings. I just kept trying to hold the rings compressed with all my 16 fingers, and it works after a while. But it's clearly easier if Yo can get an extra hand or two... There's supposed to be some tools for this. The only ones I found were the types that are used for when one wants to drop the pistons into the bores, not the other way around

Killerwhale · Post by **Killerwhale** » Thu Nov 27, 2008 7:18 pm

steve speed wrote:how did you lot get the pistons in the bore i am struggling a bit

I almost threw the shiate in the wall before i was done.....then i learned there where a tool to compress the rings...

steve speed · Post by **steve speed** » Thu Nov 27, 2008 11:48 pm

what tool ??????????????????

devlin · Post by **devlin** » Fri Nov 28, 2008 2:56 am

Ring compressor. It's a sleeve that fits over the piston with the rings installed. You adjust it so that it's snug with the piston line it up with the bore and slide the piston from the sleeve to the bore. Something like this.........

http://www.sourcingmap.com/piston-ring- ... 10825.html

HansJ · Post by **HansJ** » Fri Nov 28, 2008 8:19 am

Yup, that's the tool I found, but it wont help much since it's used when You drop pistons inte the sleeves. For our engines one would need something that's splittable after the sleeves have been dropped over the pistons. There's supposed to be compressors for this as well. If I hadn't managed to get the pistons in "manually", I'd tried to modify an oilfilter removal-tool, or using a thin leather-strap or similar.

Killerwhale · Post by **Killerwhale** » Fri Nov 28, 2008 4:35 pm

HansJ wrote:Yup, that's the tool I found, but it wont help much since it's used when You drop pistons inte the sleeves. For our engines one would need something that's splittable after the sleeves have been dropped over the pistons. There's supposed to be compressors for this as well. If I hadn't managed to get the pistons in "manually", I'd tried to modify an oilfilter removal-tool, or using a thin leather-strap or similar.

According to "Boost3" Biltema has a good one for bikeÂ´s...

steve speed · Post by **steve speed** » Fri Nov 28, 2008 4:48 pm

this is one i made this afternoon it cost Â£1

Tigcraft TRX · Post by **Tigcraft TRX** » Sat Nov 29, 2008 10:32 am

Very large cable tie works well..

steve speed · Post by **steve speed** » Sat Nov 29, 2008 12:29 pm

i have some of them but i didnt think i would be able to adjust it properly ,

steve speed · Post by **steve speed** » Tue Dec 09, 2008 9:27 pm

well its been a long haul but finally the engine is back in one piece ,,, ive run it up to temp and no leaks

so now i just need a dry day to start the running in , so that may well be next year

its a lot different , it makes a deeper noise from the end cans , and it runs a lot smoother,, fingers crossed it doesn't use as much oil !!!

and yes i did remember to fit the two bolts that hold the cam sprockets on and i did clean the tops of the pistons before i fitted the head

and a big thankyou to all that gave me advice

Kayla · Post by **Kayla** » Tue Dec 09, 2008 9:52 pm

steve speed wrote: it makes a deeper noise from the end cans

Is that because it's now running at a higher compression? That looks lovely, nice work Steve

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