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triumph rookie

USA
7 Posts

Posted - 10/10/2013 :  00:56:30  Show Profile  Reply with Quote
Hi, I am new to Triumphs and to web forums. I recently bought a 5t basket case. Some parts are missing so I plan on making this kind of stock. The most important thing is it absolutely must out run my friend's 45 cubic inch Harley! I have been told that the right side crank bearing is a week point. I need to find out what is the best cure. I have been told several different things. One was to use a 650 crank and machine out the case to receive a different bearing. I was wondering about if I could just set the 500 cylinders on 650 cases. Any help would be great and there is nothing more fun than smoking a HD!
Thanks

Grumpy

New Zealand
542 Posts

Posted - 10/10/2013 :  04:14:36  Show Profile  Visit Grumpy's Homepage  Reply with Quote
What year is your motor?
The number stamped on the top near (left hand) side of the cases will tell you this.
Number will start with 5T.....
Does it have an extra stamp in the alloy cases next to the number that looks like a wagon wheel?
Is it an alternator or Magneto engine?
If you dont know how to date it post the number and I will tell you exactly what you have.
Regardless of exactly what you have just remember these things are getting up around 50 - 60 years old so treat it kindly.
Easiest way to smoke a harley without stretching and old and possibly fragile motor is to take the Harley on in the tight twistys.
On 50 year old crappy brakes, likly to be 7" half width front hub you will have to think about stopping 200 meters before you need to so think hard before you tinker too much in an effort to get extra speed out of it.
Check out my earlier posts on my 5T, may be interesting to you.

Cheers,
Trev



1938 5T Replica
1966 T100 Cafe racer
1959 T20 Cub (in captivity)
Oh and one modern of another marque

My Triumphs don't bleed they are just marking their territory.
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f scott dundas

Australia
253 Posts

Posted - 10/10/2013 :  05:03:09  Show Profile  Reply with Quote
a stock 500cc Triumph will easily out run a 45cu inch (750cc) flathead HD. You dont have to trick up a Triumph to beat the ass of a sidevalve HD. So dont bother,dont overthink it - just put it together and enjoy!
I can vouch for this as I have a 1942 WLA (45ci) with footclutch and 3 speed stick shift in civilian trim. My Walla is a great looking old school bike and I love it,but it was made for a purpose that was not speed. My Triumph and BSAs will smoke the old HD anyday.
The endearing and funny thing about the 45ci sidevalve HDs is that the speedo is calibtrated to 120mph,but on the tank there is a plate that tells you the grade of oil to use as well as a note that says "dont exceed 65mph" Hilarious :)!
Having said all that Harley Davidson are the oldest continuously trading motorcycle company around and I like em as much as my older Pommy bikes.Scott
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triumph rookie

USA
7 Posts

Posted - 10/10/2013 :  13:19:16  Show Profile  Reply with Quote
It is a 54 5t it does have the wagon wheel stamped after the 5T it is an alternater engine. May be I should give you more of my motive on this 5t. The friendly competition is at the mile race at Wilmington Ohio. It is a straight line with plenty of shut down room, so taking him through the twisties is not an option. I actually rode his HD 750 flat head when this event was held at Maxton. It was fun and we set a record that day I think it was 93 mph it was broken a year later. We used to flat track vintage 2 strokers together but we both have to many injuries for that. So in keeping in the spirit of our competition how more fitting would it be to race a Triumph against a Harley. Now it seems safe for me to tell you gents that my first street bike is/was a panhead and I currently ride to work on an 83 flht (shovelhead) So nothing against HD. This 5t basket came with an extra twin carb pre unit hard tail frame, I would like to build that as an all out racer. That is why I was wondering about a 650 bottom end with a 500 top end and it would keep me legal as far as the c.c. limit.
Thanks,
Brandon
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f scott dundas

Australia
253 Posts

Posted - 10/15/2013 :  17:53:55  Show Profile  Reply with Quote
If the motor is a full alloy competition model just put it together and it should blow the old flathead HD away.
If it is a cast iron top-end try and get an alloy head,flow and polish the ports and fit twin carbs. For some extra grunt fit a high lift cam and high compression pistons and that should do it.
I think you will find that a 650 bottom end and a 500 top end won't fit together due to the different crankcase stud pattern so you may be wasting your time with that idea.
Good luck with it. I would sure like to see the race!
Scott
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Grumpy

New Zealand
542 Posts

Posted - 10/16/2013 :  02:14:41  Show Profile  Visit Grumpy's Homepage  Reply with Quote
Would need the engine number to confirm but very likly you have a earlier 1.0in roller bearing.
Mid season in 1954 engine changed to a 1.125in ball journal for the right hand main bearing but only on about 50 motors only before reverting back to teh smaller bearing for rest of model year.
1955 on the larger bearing was fitted and changed from the roller to a ball jornal bearing.
The 650/500 are interchangeable but you will have to mill some of the case to make it fit.
In my opinion not alot to be gained.
If you can hunt down an alloy head, and as Scot says go to a higher compresion piston.
You are likly to be at 7:1
Twin carbs will also give you a bit.
Stock out of the box one of these should give you around 90mph, no reason you shouldn't get that numer to the magical 100mph.
Look at you unsprung weight, guards, seat, lights etc, take all that rubbish of and you may get another 2-5 mph.
75% of any power (speed) gains will come from work on the top end (head)
I get 80mph out of my stock standard 53 5T engine sitting up grinning like a madman.

As an aside one of these 1938 5T with a supercharger fitted holds in perpetuality the class record at Broocklands of about 119mph, I could be wrong on the exact number so dont quote me.
Record will never be broken as off course Broocklands speed bowl did not reopen after the war.
in South Australia a speed twin set a world record 12 hours and 24 hour record.


Have fun,
Trev


1938 5T Replica
1966 T100 Cafe racer
1959 T20 Cub (in captivity)
Oh and one modern of another marque

My Triumphs don't bleed they are just marking their territory.
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triumph rookie

USA
7 Posts

Posted - 10/17/2013 :  01:14:16  Show Profile  Reply with Quote
I currently have a cast iron head I was considering getting a spare cast head they are somewhat inexpensive and porting it and putting larger intake valves in it. Being that the cast head is the seat it makes it even easier to go to larger valve. I Can do this myself. I am open to an aluminum head but it had to be available in 1954 or earlier per the rule book. I could use a give part that is made in the 1970s as long as it was available by 1954. I got to make it a class I have been told there was a 2 different size bearings on right side journal. I was also told that some of the early 500 had week rods. To be honest I don't know what you would call "early". I currently have .10 over pistons I don't know how to tell what the compression ratio
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Grumpy

New Zealand
542 Posts

Posted - 10/17/2013 :  03:13:24  Show Profile  Visit Grumpy's Homepage  Reply with Quote
Alloy head was available for the T100 from 1951.

Cheers,
Trev


1938 5T Replica
1966 T100 Cafe racer
1959 T20 Cub (in captivity)
Oh and one modern of another marque

My Triumphs don't bleed they are just marking their territory.
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triumph rookie

USA
7 Posts

Posted - 10/17/2013 :  13:06:24  Show Profile  Reply with Quote
Sorry guys my computer stoped in the middle of my last post. I was wondering is there a way to figure out what the compression ratio of these piston are. Thanks for all the info guys this is so much help!
Thanks,
Brandon
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f scott dundas

Australia
253 Posts

Posted - 10/17/2013 :  20:07:11  Show Profile  Reply with Quote
If they have a high dome they are probably 9:1 or possibly higher. If they are flat they could be as low as 7:1. Clean off any carbon and have a close look at what is stamped into the top of the piston. I have seen the comp ratio stamped in this area. Alternatively bore the cylinders to +.20 over and buy a set of the highest comp pistons you can get ie 9.5 or 10:1.
Scott
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Grumpy

New Zealand
542 Posts

Posted - 10/18/2013 :  00:56:43  Show Profile  Visit Grumpy's Homepage  Reply with Quote
Take a look at your piston, flat top with very small pockets for the valves............very likly 7:1

1938 5T Replica
1966 T100 Cafe racer
1959 T20 Cub (in captivity)
Oh and one modern of another marque

My Triumphs don't bleed they are just marking their territory.
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triumph rookie

USA
7 Posts

Posted - 10/19/2013 :  20:38:23  Show Profile  Reply with Quote
I looked at my pistons and the relief cut in the piston is half the diameter of the valve. The dome looks tall to me. Maybe I could post a picture Ill give it a try.
Thanks,
Brandon
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f scott dundas

Australia
253 Posts

Posted - 10/21/2013 :  17:36:27  Show Profile  Reply with Quote
They sound like they could be relatively high compression pistons. To avoid any doubt bore the cylinders to +.20 and buy a set of 9:1 pistons or higher and you take the guess work out of the equation!
I would'nt go much above 9:1 or you may start blowing headgaskets.
Scott
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triumph rookie

USA
7 Posts

Posted - 03/14/2014 :  12:34:36  Show Profile  Reply with Quote
Hey, I have been making slow progress I ended up rebuilding the transmission. I decided to split the cases and found it has 650 rods with inserts I was glad for that. So I get back to the pistons and found that there are not a lot of choices and there is a wide variety on the prices. What do you guys recommend? LS Harris, Old hepolite, New hepolite, JP, or some just say Taiwan? thanks for any help.
Brandon
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Grumpy

New Zealand
542 Posts

Posted - 03/14/2014 :  15:04:54  Show Profile  Visit Grumpy's Homepage  Reply with Quote
Used L F Harris in my rebuild, no makers mark or similar on them so very likly they are Taiwanese.
No issues with them.

1938 5T Replica
1966 T100 Cafe racer
1959 T20 Cub (in captivity)
Oh and one modern of another marque

My Triumphs don't bleed they are just marking their territory.
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triumph rookie

USA
7 Posts

Posted - 03/19/2014 :  00:27:16  Show Profile  Reply with Quote
Thanks Grumpy I just ordered a set. Do you remember what clearance you set yours up at? I am getting some conflicting information.
Thanks
Brandon
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