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New purchase 1968 Triumph TR25W (BSA nightmare)
#809955 05/23/20 12:01 am
Joined: May 2020
Posts: 4
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Hey new member 🤘

Just bought a 68 TR25W with the lovely BSA b25 engine single seemingly renowned for bad engine issues 😅

I'm looking to turn her into a old school Mx bike on the road 😅 I'm basically looking for a list of engine mods required to get her running peppy but not a Trainwreck.

I'm looking into getting forged conrods and shimming the barrel. I've heard of modifications of adding oil filters and redirecting oil flow is there anything else to consider? (I've heard of grinding the decompression lever arm to reduce weight from that tappet)

Will be making my own stainless pipes and possibly looking at larger carbs with some flow work (recommendations would be great 🤘)

I'd love to take her on my yearly trip to Morocco but the reliability scares me and my 2004 t100 bonnie is my go to 😅

Frame modifications would be great to hear about for example changing head angle I have a welding jig table so I can dial it in if you have a good angle adjustment 🤘

I know that's loads to take in and each part is highly detailed links to other. Threads would be epic too 🤘
Thanks

Callum


2004 Triumph Bonneville t100 (in pieces)
1974 Honda CD175 (two engines1 good, 1 very bad further investigation required)
1978 Triumph TR25W (in transit from the land of freedom units)
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Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #809956 05/23/20 12:11 am
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Rupert Ratio wrote the book on this. its all there, essential for unit singles.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #809957 05/23/20 12:17 am
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+1 for Gavin, those books are invaluable. Check out the series of YouTube vids by Michael Waller of Britannia Motors. He has done most of what you are looking at especially the frame mods.

Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #809963 05/23/20 1:57 am
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Ed V . has some crank mods to improve big end oil issues for the b25

https://www.shopevengineering.com/techtips

.

Re: New purchase 1968 Triumph TR25W (BSA nightmare)
gavin eisler #810374 05/26/20 6:49 pm
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Ordered from ratio publishing 🤘


2004 Triumph Bonneville t100 (in pieces)
1974 Honda CD175 (two engines1 good, 1 very bad further investigation required)
1978 Triumph TR25W (in transit from the land of freedom units)
Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Dave Martin #810375 05/26/20 6:50 pm
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Wicked I've had him on in the background for the last few days so got a fair few ideas what's the engine mods people have done for increasing reliability? Does anything need to be done on the crank itself of would the forged upgrade do the job?


2004 Triumph Bonneville t100 (in pieces)
1974 Honda CD175 (two engines1 good, 1 very bad further investigation required)
1978 Triumph TR25W (in transit from the land of freedom units)
Re: New purchase 1968 Triumph TR25W (BSA nightmare)
quinten #810376 05/26/20 6:51 pm
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Wicked I'll message him about what to do on my crank and casings to increase oil flow 🤘


2004 Triumph Bonneville t100 (in pieces)
1974 Honda CD175 (two engines1 good, 1 very bad further investigation required)
1978 Triumph TR25W (in transit from the land of freedom units)
Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #810445 05/27/20 4:09 am
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Fix oil flow issues and add an oil filter. The motor doesn't really need to be made peppier so redirect that money to make it a better rider.

Don't cut the frame and change the steering angle, there is nothing wrong with it.. Better to fabricate a 1" longer swing arm, put on a very good set of shocks, perhaps 13.5" long and put on some decent forks, like Ceriani or Betor forks. That is if you are looking for something a bit better handling rougher terrain.

Good luck!


check out: www.bsaunitsingles.com
2500 BSA part numbers with inventory in stock just for the unit singles!
Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #810456 05/27/20 6:37 am
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Forget the porting, the bike hasn’t got enough cc’s to make up for what your going to loose midrange by making the ports bigger. If you want something with more pep look out for a B44 engine to drop straight in.


beerchug

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Re: New purchase 1968 Triumph TR25W (BSA nightmare)
Renewfab #810464 05/27/20 9:38 am
Joined: Dec 2004
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The con rod snaps when the big end seizes, fit T100 shells out of Al/Sn without the oil hole not the OEM whitemetal rubbish, fit a late T100 con rod without oil hole and do all the oil mods so the oil pressure is good, fit an oil filter and use a good oil. A blueprinted B25 engine will give out 100hp per litre, it thrives on revs so use the full rev range and do not change from 3rd to 4th until you see 8k rpm.


Moderated by  Allan G, Jon W. Whitley 

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