TriCub wrote:Maintaining the shape of the top part of the transfer ports is the most critical so taking 2 mm from the top and 5mm for the bottom should work ok. That gives only a little bit of barrel to remove to get the match at the transfer top. Be careful after the sleeves goes into the barrel(don't press it in) as it will probably not be round anymore.
I should clarify the bit about not pressing in. Sleeve has to be a press fit but if you press it in there is a chance that a sharp port edge will tear away part of the cylinder on the way in. You have to heat the cylinder then drop in the sleeve giving you about 2 seconds to line up the ports.
George, thanks for the explanation as this is something I have not done before, there is a wealth of local knowledge. My machinist friend heated the cylinders before pressing the sleeves out, a job he has done plenty of times and if you look closely you can see where the sleeve scraped it's way out. Another Mate is the Motorcycle Mechanic and has been advising me as well re what will and won't work.
JC1 wrote:Greg, you got me thinking it thro to see what's involved in matching it all up, so for what its worth here's a few more tho'ts:
(I can't do much else at the moment)
Looks like the boost port area may need a fair bit of attention too. It appears to be a fair bit wider in the 44M liner & cylinder, as is the inlet tract where it splays around that boost port tract, which may mean that you'll need to 'fill in' the boost port tract a little in the 44M cylinder. Otherwise the inner edges of the Cota liner's inlet port may open into the boost port tract of the 44M cylinder (if that makes sense)
As for port heights, if my maths are correct and going by the dimensions I have for VR Cappra & 247 Cota port heights, if you take the 2mm off the top of the 44M cylinder (& 5mm off the bottom) to suit the Cota liner/engine, the exhaust port should take care of itself (tho it'll be considerably larger all round in the 44M cylinder than in the Cota liner - not necessarily a good thing, but it should still work).
Then it looks like the top of the transfer & boost port ducts in the 44M cylinder will have to be raised about 2mm & the top of the splayed inlet ducts in the cylinder will have to be raised about 3mm, to suit the Cota liner. The bottom of the inlet ducts in the 44M cylinder will be about 6mm lower than in the Cota liner which I'd think should be filled as per the post above.
Those are ball-park figures assuming the 44M cylinder is the same as the VR, and that the angle of the tops of the ports in the liners (VR/44M & Cota) are the same.
Seems to me that's quite do-able for a man of your skills - even if a lot of work.
But I'm wondering how you're going to fit a side-port barrel into a double downtube 242 frame. Convert it to single downtube? Or pull the downtubes in close to each other?
No doubt you'll already have a solution in mind.
John, the port heights diagram were approximations of the cylinders without the Sleeves! Below is another drawing I have done with approximate measurements of liners but have not measured to inlet tract yet. Well spotted with regards to side port instead of Centre port and I think bringing the twin downtubes together will make it a bandaid modification so I am thinking a bigger round downtube. There is quite a bit of room to play with as the standard exhaust is in front of the downtubes and I will have a header pipe similar to or same as 247.
Here is a photo looking in the inlets, luckily have provided me with a bolt up manifold so I can reduce the passage to fine tune for low speed without removing the cylinder. The spigot needs to be reworked to suit 26 mm carby and may be elevated to clear the clutch cable?
Yes there is a fair bit to consider, some of it way over my head but I think I am heading in the right direction. Imagine 247 reliability with 242 Handling!
David, just thinking about your Alpina magneto cover, maybe make an adaptor plate and cut down a TY cover something like what have done with TLM 220/260 to fit a bigger weight onto a trail bike Magneto?
The closest thing to a TLM is the MTX 200, some parts interchange: