|
|
Post by LC_BOTT on Oct 11, 2020 13:22:16 GMT 1
Hi all, very slowly building an N1 from frame and cases, need some barrels and wondering what the suffix cast into the barrels should be?? and does it really matter if the barrels are 31K/1UA etc and not as factory fitted?
|
|
|
|
Post by Shytalk on Oct 11, 2020 14:26:55 GMT 1
31K and not really.
|
|
|
|
Post by midlifecrisisrd on Oct 11, 2020 18:00:57 GMT 1
As above
These days when they are getting rarer and pricey just fit what you can get unless you are going anorak 🧐
Steve
|
|
|
|
Post by JonW on Oct 12, 2020 4:31:19 GMT 1
Kinda agree really, get what you can. Same with heads and carbs. you can interchange around on the 31K and 1UA with no problems.
|
|
|
|
Post by LC_BOTT on Oct 12, 2020 8:52:20 GMT 1
Thanks, that was what I was thinking/hoping, got a couple of sets of 1UA barrels I can use, not really wanting to buy any more, not doing too many more rebuilds or projects, it'll be a chance to use some spares up  Not going for a concourse/original resto, but just a nice looker that might get ridden for once. |
|
|
|
Post by steve63 on Oct 12, 2020 12:56:20 GMT 1
Thanks, that was what I was thinking/hoping, got a couple of sets of 1UA barrels I can use, not really wanting to buy any more, not doing too many more rebuilds or projects, it'll be a chance to use some spares up Not going for a concourse/original resto, but just a nice looker that might get ridden for once. The 1UA cylinder porting looks like it is a set up that would give more power than a std. 31K barrel. I say that because the inlet ports are much bigger than the 31K and on the production tuned 31K barrels I had the inlets had been made much bigger and were similar to the standard F2 cylinders. |
|
|
|
Post by JonW on Oct 12, 2020 13:10:56 GMT 1
if Yam is to be believed, 63 vs 59bhp... different combustion chamber design in the head and pipes as well on the 1UA is said to help that as well.
|
|
|
|
Post by midlifecrisisrd on Oct 12, 2020 14:13:16 GMT 1
if Yam is to be believed, 63 vs 59bhp... different combustion chamber design in the head and pipes as well on the 1UA is said to help that as well. All UK bikes had the 31k head, we never got the 1ua one for some reason ☹ Steve |
|
|
|
Post by steve63 on Oct 12, 2020 17:48:55 GMT 1
if Yam is to be believed, 63 vs 59bhp... different combustion chamber design in the head and pipes as well on the 1UA is said to help that as well. I take the Yamahan figures with a pinch of salt but the difference between them of 4hp is maybe more believable. In reality though a mate of mine bought an F2 for racing. he had it tuned but it just seemed to lose mid range without gaining much at all at the top. It just didn't rev. My other mates F1 was a flyer. We decided it was the pipes so I welded an 12mm drill to a piece of bar and drilled some holes into the pipe through the silencer. I don't think it changed it much. I think it boiled down the the ignition. It was as if the F2 was set to have a lower rev limit, something like 9,500rpm where the F1 would rev on and on. I think they did a bit of a swap around and the F2 engine in the F1 with the F1 pipes and ignition was OK. I put an F1 engine and the complete wiring harness/ignition in my 4L0 and it was a flyer. |
|
|
|
Post by midlifecrisisrd on Oct 12, 2020 17:59:15 GMT 1
Fair point on the ignition
If you look at the peak power revs they tell a story
31k lc2 - 9k
31k n/f - 9.5k
F2 - 8.5k
Vast variation between individual bikes too
I've ridden standard fully rebuilt lc2's that were bland and old tatty ones that were a bit crazy
Steve
|
|
|
|
Post by JonW on Oct 12, 2020 22:54:29 GMT 1
Thats why blue printing engines was always the go, production tolerances make individual bikes work better than others.
Didnt know UK bikes didnt get the 1UA head.
|
|
