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Honda VT250F Engine Swap (Update: Wiring Problem)

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by PeskySheepy, May 22, 2009.

  1. Heya guys,

    I've been scouring the internet and ringing local bike shops and the like but have yet figure out how to proceed.

    I recently brought an 83 Honda VT250F for a couple hundred, the owner was unable to start it for me but assured me it was a camchain issue and gave me a couple new chains he had laying around.

    I managed to get it started when I got it home and the noise it was making was alot deeper than the cam chains.

    I stripped the engine right back, split the block and found the crankshaft was pretty scratched up and the bearings were tiny bits of twisted melted metal.

    Awesome! : /

    I figured I'd be able to get the crank linished and a couple new bearings fitted but the bike shops and mechanics I've rang have all pretty much laughed at me, wouldn't touch the crank with a ten foot pole and basically told me to throw the bike out and start again. Literally.

    So alas, my story continues. I've got a few bikes already so this one is a bit of a project bike so I'm not ready to give up yet.

    One guy I talked to said I could probably chuck a different engine in there... He had a rebuilt 1990 VTR engine up for grabs, said it was basically the same engine and with a couple mods would probably fit... I've also been told the Spada and Integra engines will also fit.

    Anyone know for certain what I could fit in instead of the 83 engine?
  2. Do a bit of a search on this forum. It has been dicussed here before. The commonality I belive is between the spada and the vtr. not the earlier engines.

    Maybe talk to a grey importer about getting an engine for you. They may be able to grab one in their next shipment
  3. Heya, thanks for that.

    Picked up a rebuilt 1990 VTR engine.... wasn't sure if it would be cross compatable but bit the bullet and decided to have a go for at it anyway.

    VTR engine fits the 83 VT frame like a glove. Everything lines up and sits where it should. Have swapped the heads on the VTR to my VT heads and have changed the cam chains and sprockets to suit the single row chain and the like but otherwise its smooth sailing and I'm pretty stoked.

    Might post some photo's when I'm done and everythings running and will let you guys know of any further problems I encounter so those with older VT's who find themselves in similair positions know that there are alternative options. : )
  4. Nice. Is there a difference in valve timing in the VT head? Has it improved power?
  5. Doesn't an 83 vt250f have a hydraulic clutch?
  6. Change of plans. I picked up another vtr engine with a roasty toasty crankshaft but a good top end and used the heads, chains ect on my vtr engine so I didn't have to use the VT heads.

    Looks better and I daresay the engine will probably like it more.

    @ DTwo - Clutch came with the VTR engine so I used that.

    I'm ready to set the tappets but can't find anything about the tappet clearance in the manual. Anyone know what it is for a 1990 VTR 250?

    Edit - Nevermind. Found it... was looking in the wrong section of the manual. :/
  7. Engine is well and truely in. I had a super horrible battle getting the timing right, three weekends worth in fact. :/

    Anyway, the engine turns over but I'm unable to start it still, I've traced the problem to the wiring but have spent the past few days splicing and soldering and have yet to get anywhere.

    I've kept the original VT 250 wiring so I wouldn't have to change the carbies and the like. It all fits pretty much flush with the spada engine except on the clutch plate side.

    The wireing that connects the cylinder pulse generators to the harness is different between the two engines. On the VT engine its a 6 pin coupler. On the spada engine its a 4 pin and a seperate 2 pin coupler.

    I've connected it all up as best I can and the front spark plug fires normally but the rear sparks maybe a half a dozen times per revolution. If I alter the wiring I can make the front plug fire rapidly and the rear normally but I'm unable to get both normalised.

    I've tried to sets of wiring for that section, two sets of pulse generators ect to no avail.

    Anyone have any ideas on where I might be going wrong? I read somewhere ages ago that it could be a voltage thing, they require different levels of voltage or something along those lines. Does that make any sense?