triumph twenty one top end questions and t100 bottom end questions

[dunboyne]

ive been working on a project , a 1972 triumph daytona with a triumph twenty one engine . the bike had not been together in a decade or two . the engine smoked a lot and upon inspection there was too much wear in the valve guides . in the box of parts i found another head which looks the same except the valves are larger diameter ,everything else measures up the same , it is in better condition so i used it .the newer head had 73b stamped on it .
since then there seems to be more clatter from the top end than there was before and im wondering why ? .
are the rocker boxes interchangeable on these ?, its possible they got mixed up . i know the pushrods are different lengths .

on another note ... does anyone know where i might get a parts diagram or e manual for a pre unit t100 ?

and lastly .. i am building a triton with a 58 dommie frame . if you had a choice of a t100 pre unit engine or a 1962 trophy 650 engine for the dommie frame which would you pick ? neither have been in the frame yet so engine mounts etc will need to be sourced.

cheers .

[wetdog]

pre unit any day for me , the unit looks in the wonge place and rear chain length can give problems

[Bomber]

I have to agree with Wetdog, a unit construction motor looks so wrong in any Featherbed. Whereas a pre unit fills the frame up better and looks the part

Frank

[Rex]

ive been working on a project , a 1972 triumph daytona with a triumph twenty one engine . the bike had not been together in a decade or two . the engine smoked a lot and upon inspection there was too much wear in the valve guides . in the box of parts i found another head which looks the same except the valves are larger diameter ,everything else measures up the same , it is in better condition so i used it .the newer head had 73b stamped on it [/i].

The early 350s had smaller valves (can't recall if it was inlet or exhaust) but they soon went to the later larger 5TA type and then larger again for the T90. More clatter indicates worn parts or incorrect rocker gaps. Checked them since you fitted this head?

on another note ... does anyone know where i might get a parts diagram or e manual for a pre unit t100 ?

Google it, there's loads on the Net, on Bruce Main-Smith for a paper copy.

and lastly .. i am building a triton with a 58 dommie frame . if you had a choice of a t100 pre unit engine or a 1962 trophy 650 engine for the dommie frame which would you pick ?
 
Preunit, although a 650 preunit would be the ideal one to have.

[john.k]

You mention BMS publications,they seem to me to have ceased.Is this the case or am I just old and silly.Regards John.

[dunboyne]

thanks for the replies lads . i've been unwell so have not been near the triton or the 21 much since . i did strip the t100 motor down and noticed there was a good bit of play on the cam bush's where they fit into the casing beside the cam  gear . i'm presuming there should be no play here .i'll go looking for a manual asap. i was told there is race cams in this engine ,is there any way of knowing ?
from what i gather the engine is a 1951 model ?, engine number t100 1553 na .

[wetdog]

looks like a 3134 , maybe polished off , 3134 inlet and ex is a good combination (thruxten) also use same profile bsa spitfire , I have used with R followers and the bike go well . ideal for tritons

[dunboyne]

yup both of the cams have 3134 stamped on them . any recommendations on where i would get a timing side bush for this engine ?. there is too much play there even though the cam fits in the bush just fine . the exhaust cam timing side bush is 1.120 inch whereas the inlet is at 1.110 inch , the 1.120 bush fits both casing holes fine . it looks like it was assembled like this , god knows why .
in other news today ... i think ive found another engine number , the t100 1553 na number is on the right crankcase half and the numbers 3t75501 are on the left one . im unsure but i think its an early style crank in it .

[chaterlea25]

Hi,
The cam bushes should be an interference (shrink) fit in the cases
If the bush/s were rotating in the alloy they will have worn the alloy oval which will need trueing up and oversize bushes made to suit
Then the inner bores should be line reamed or bored to fit the cam itself,

$ £ & €'s all the way 

HTH
John

[dunboyne]

i do not think the bush had spun and worn the casing , the loose bush is on the inlet cam . if i remove the bush from the exhaust cam and put it in to the hole for the inlet cam bush it fits fine . the both of them look different and they measure different .the inlet cam bush is 0.010 inch smaller and im unsure if its the proper bush . ill get a pic and perhaps the difference can be seen (not the size but the style of bush) . one has 4 holes and an oilway on the inside (this one fits fine) and one has 2 simple holes and no oilways.

[chaterlea25]

Hi Again
The bushes should not be able to slide in and out of the housings
Have you accurately measured the crankcase bush bores?
In order to see if its the cases or bushes are the problem

Usually there are matching numbers on each half crankcase on one of the lugs
these were done at production to keep matching pairs together

With a name like Dunboyne I'm assuming you are Irish based?
I am as well !!
If you want to send me a pm I can give you my email address to send photos to
I may be able to help with the engineering issues

John

[dunboyne]

hi chaterlea25
indeed i am based in ireland , i lived on the old dunboyne circuit growing up and my wife and myself started off the motor club there and organised the first of the recent reunions .it had long been a dream of mine to hear the old race bikes of the 50s and 60s ride through the town again . i knew / know some of the guys that raced cars and bikes there back in the day . i left the club since , club politics is not my thing .

ill pm you my email address .

ive discovered more numbers on the casings of this engine and going by numbers stamped it appears to be a t100 left crankcase and a 3ta right crankcase . the last guy that had it had not heard it run but thought it was run on methanol last .
just to clarify , if i use the bush that is on the exhaust cam (the cam with no play in the bushes) i would need to heat the crankcase to get the bush into the bush bore . my thinking at the moment is that the wrong bush was fitted to the inlet cam and i can only presume it made a racket upon assembly and starting and it was left alone until it got to me . i would expect a bit more wear on the cam itself if it had ran a while in this condition . i think new bushes will do the trick .

[wetdog]

does it look like it was run on meth and is it coverd in sticky "R" . sounds like a lash up to me and a ground up rebuild would be best , where are you getting a spark from to run the engine ?

[dunboyne]

does it look like it was run on meth and is it coverd in sticky "R" . sounds like a lash up to me and a ground up rebuild would be best , where are you getting a spark from to run the engine ?

it has a magneto with it but i havent really examined it yet . there was sticky type residue all over the casing internals alright .

[wetdog]

where does the mag fit ? I think ive got it wronge , its not a 3ta right hand case its a 3t ? im mixing unit with pre unit