Sprint ST (1050) Drag Engine Build

[psykown]

Long time no see peeps! it's been a few months tanks to life, moving, new job, new home shop, the works. Now its time to start the fun again! Recently I finished rebuilding a Sprint ST and in the process I ended up with an extra almost good engine. I'll get some pics of the "finished" bike later but man is she fun! Fell in love with the triple engine with my Street Triple and the Sprint really is just her bigger more ticket prone sister lol. So the rough goal of this project will be the following:

1: 200(ish)hp
2: Semi streetable, I dont want a garage or trackday queen
3: Low(ish) cost, thankfully I do have my own mill so custom parts are a must
4: Longevity is cool but fun is cooler

This is ultimately my extra engine so I want to have fun with it over just building it for practicality, if ya'll have ideas or recommendations please let me know! I am leaning toward a fleabay turbo build, have a friend that can easily weld a custom airbox and I have enough machining skills to fake my way through any custom work. I am not opposed to porting, polishing, making some custom pistons, etc, basically the world is my oyster as long as I can make it myself, lets have some fun!!! (PS if anyone here is in the Palm Coast Fl area I am down to race when she is done )

 

[psykown]

Started off by removing all the side covers and giving them good clean and Cerakote job, why? because I had it lying around lol.

Removed the head and got a nice and not so nice surprise

Cam bearings and cams looked excellent, I really was worried that this bike would be thrashed and in worse shape, hte bad new cam a little farther in though.

The center cylinder was rough to say the least. Thankfully with the sprint they are drop in sleeve so easily replaceable but still more $$$.
May give it an attempt at boring it out but I think this one is a little too rough to save.
Next time on Dragonball Z the bottom end comes apart, will it be trash? will it be pristine? tune in next time for the answer!

 

[matty]

Good stuff bring it on. A big triple and triumph fan here, Never had a 1050 only the Kawasaki triple 500s and in triumphs just old T150 tridents and my sprophy mongrel 1996 900cc carbed model, and used to have a 2016 tiger 800 XCX .
John blor needed a wiener to re launch triumph back in the early 90s and he made the early hinkley triples strong and i would say a fair degree of over engineering in their blood .
Should be a good candidate for a reliable build.
A anecdote on the rough neglected bore. Mate bought a 900 INJection motor from a scrapyard for £50, it was rock solid had been sat plugs out forever from what he could tell. he had a Rolling Frame he wanted to track day, and had all the ancillaries looms clocks etc.
Stripping was the obvious thing, but if you knew tony you would know he is an animal and that was not going to happen until it absolutely had to.
A bore scope showed Rust in all bores it looked horrible in there, He soaked the bores in diesel for a week and ignited any left in via the plug hole with and oxy acet torch.
Then wile still warm filled the chambers with penol graphite based penatrating fluid and left it three days soaking it until the can was empty.
Still solid .
I sujested the molases and water option, he mixed up a 9 to 1 molases mix in a coke bottle and poured it in left it and after three days it was KTM orange in those bores and still rock solid. He got the glock out with a piece of 8mm copper pipe and nylon rope pushed through it like a brush, then he went back to the molases again. trided it everyday for a week and still solid.
Threw the motor under the bench full of molases and plugs back in and it sat there 4 days tried it and it moved just a little at first, but it soon freed off and it was turning over fine.
loads of diesel thrown down the bores and kept spinning it over with the windy gun.
Was discusting what came out but it ended up looking clean enough in the end.
I was expecting it to smoe for England but, to my amasement it ran just a little haze on initial start up then it even ran quiet and you know they all clatter a bit.
If i had not whitnessed much of this i would have doubted it, but it is what it is and testiment to just how tough these motors can be.
It was built and sold shortly after, so no idea how long it survived, but from cassual observation it was fine.
All the best with your build looking foreward to it.

 

[Shinyribs]

Subbed. This looks like fun

 

[psykown]

Yeah the triples are hands down my favorite engine so far, fell in love with the 675 and the 1050 stock doesn't disappoint either! Swapped a ZX6R front end onto here for more of a Speed triple feel and so far it does not disappoint!

Next week the goal is to tear down the bottom end completely and have a proper part list ready and then its on to deciding want I want to machine myself and what I want to buy. Then its time to clean everything and Cerakote anything left to sort of mostly match, some of the cover plates I already have a forest green and they came out pretty decent for a home job.

 

[matty]

Like the color choice, looks good. .

 

[psykown]

Thanks! I purposely havent clear coated it so it will rough up a bit, and then probably next winter I'll clear coat that "used" look in, giving it a bit of a rat rod look. Fingers crossed it comes out how I hope lol Right now I am just trying to decide on the metal tank versus the plastic tank. Plastic is painted to match, metal needs a little work before I can paint it lol

 

[psykown]

Not a huge update as I have been busy on the mill this week breaking bits lol I did get the clutch hub out, oil pump out, and shift assy out. Now its time to fight that case apart, so far the font of the case is loose the rear does not want to budge at all though. Not a single visible bolt is left in it, but it does look like there is a good bit more rtv than the first engine I pulled apart. I am starting to worry someone else has done some work to this one already.

 

[matty]

Not a huge update as I have been busy on the mill this week breaking bits lol I did get the clutch hub out, oil pump out, and shift assy out. Now its time to fight that case apart, so far the font of the case is loose the rear does not want to budge at all though. Not a single visible bolt is left in it, but it does look like there is a good bit more rtv than the first engine I pulled apart. I am starting to worry someone else has done some work to this one already.

heat gun ! And if its tight get a oil drum cut the side out and throw it in diesel for a week. then re heat again.

 

[psykown]

I didnt think of that, I keep forgetting I found a solid new heat gun in the dumpster a few months back, will update over the weekend!

 

[matty]

I didnt think of that, I keep forgetting I found a solid new heat gun in the dumpster a few months back, will update over the weekend!

Remember be gentle brute force and ignorance busts stuff. Just sayin

 

[psykown]

For sure! i got half of the rear of the engine worked somwehat loose in between a few other jobs on the CNC today, tomorrow I'll fight with the other half. So far its just been heat then work the two little tabs nice and easy till everything starts to move freely

 

[psykown]

Engine is slowly working loose but man its a Pita. Had to mix it up a little so I am getting some rough dimensions of the stock piston, if anyone has some 4032 aluminum they want to sell let me know! primarily using this for wrist pin to piston face height, need to learn more about designing a piston for turbo application.

 

[matty]

Engine is slowly working loose but man its a Pita. Had to mix it up a little so I am getting some rough dimensions of the stock piston, if anyone has some 4032 aluminum they want to sell let me know! primarily using this for wrist pin to piston face height, need to learn more about designing a piston for turbo application.

Scrap cummins pistons and cast your own, get them out of wrecked DAF engines here. OPEL vauhall or Chevrolett pistons are ok too. Dare say others like Skoda/ VW Seat or citeroen / PSA would be decent too.

 

[psykown]

I hadn't thought of that! I think I've got a few friends I get them from for damn near free as well.

 

[psykown]

This weekend I got the head disassembled and am starting to clean everything up. as you can see it was a little rusty but to my surprise it was all surface rust for the most part. It does appear that the valve guides are leaking oil as there is an oily streak from it in the exhaust ports so that I will replace.

Got to work cleaning everything up and it really does look pretty good! The only other thing I think is maaaybe not worth saving are the exhaust valves, even after a cleanup it looks like there is still a good bit of pitting along the seat angle. I don't think they will lap out.

 

[psykown]

And case is apart! The inside looks excellent. transmission looks solid, and cranks looks almos perfect! I think it’ll be a prime candidate to blow up with a turbo

 

[psykown]

Sorry for the lack of content here, had some slightly more expensive things to take care of. In the mean time, I have Cerakote some OEM forks, calipers, and triple clamps and installed them back on the Sprint and its looking sharp, need to pick up some Coyote Tan for the fender and then the front end suspension will be squared away. Also got my hands on a bunch of 7075 aluminum billet and sheet so I think the front end will be redesigned. Going to make a nicer dash stay and some sleek adventure style fairings for this beast.

 

[Shinyribs]

We're gonna need some pictures of the cerakote, sir!

 

[psykown]

My bad! I am not great at it yet, but it sure makes me look better than I am!