VTR250 cam chain replacement

[328FTW]

I've looked at the manuals and they show disassembly of the main engine but not specifics about the cam chains. I got a 30,000km motor with great looking internals for $30 that has a snapped cam chain from an accident that pushed part of the frame into the motor snapping the chain. I have another chain and I have put it on but it basically required disassembling the entire motor. It was fine because I needed to check the valves were ok anyway but did I miss something here? It would of been 1000x easier if you didn't have to lift the crank slightly to slide the new chain in or they put a joiner link in the chain somewhere.

Just seemed kinda silly the chains are so buried like that.

[bsasuper]

remove the tensioners, then remove the camshafts, might have to remove the camchain guides as well, chain will then be able to be removed.

[328FTW]

I couldn't get it past the end of the crank though was the issue. The topend was easy. It's the bottomend that seems like I'm overlooking something, like I said I had to lift the crank out a bit then put it all back togetheragain

[ducatilover]

Been a while since I've been in one, but the best way to do it is split the chain, join to the old and turn the engine over to bring the new chain through.
Otherwise, tip the engine upside down and feed the chain in from the bottom if you can so you can get it past the bottom gear (unless you can remove it)

[328FTW]

I didn't see a dropout link in it anywhere either. Doesn't matter, I pulled it to bits to check the gears to because being crashed I didn't want to find 3rd gear had teeth missing from when it came to a dead stop, I've had gearboxes like that before.

Just seemed rather strange, I prefer the old roller chains to those multiplate deals. I dunno if this thing is going to run or not. Head off one motor, cams from another, gear linkages from another. Going to look funny when I finish it and all the covers, heads etc are different colours

[nzspokes]

A rattle can will fix that

[ducatilover]

I didn't see a dropout link in it anywhere either. Doesn't matter, I pulled it to bits to check the gears to because being crashed I didn't want to find 3rd gear had teeth missing from when it came to a dead stop, I've had gearboxes like that before.

Just seemed rather strange, I prefer the old roller chains to those multiplate deals. I dunno if this thing is going to run or not. Head off one motor, cams from another, gear linkages from another. Going to look funny when I finish it and all the covers, heads etc are different colours

What could possibly go wrong?

[328FTW]

Had a bike mechanic come in today by coincidence, was a little late but he told me how to do it. The links do punch out allowing you to wind a new chain in and around the motor. I was afraid of doing that and having it fall apart because you shouldn't do that. But at least I know now

I can also now name a list of things different between a later motor and the early ones. Might be useful to some desperate soul looking for info one day.

The heads are different, not sure about chamber size but the newer heads feed oil from the block, old motor feeds oil from external metal oil lines. At least it appears that way, didn't check to see if there is a headgasket difference due to the oil feed differences.

Cam caps are different, the early ones feed the oil across from one to the other using a metal pipe that bolts down on top, the newer ones seem to use a more integrated pipe with O rings that is part of the 2 main caps.

Block is slightly different, the newer block has a different shifter arrangement. You cannot install the old shifter arrangement into it, there is a different stud layout. Also the aforementioned external oil line to the head, where it feeds from there is no hole for it, blanked off and to use the older heads you need to drill and tap this. The oil gallery is there though, massive relief when I broke through into it to tap out the block for the banjo bolt.

The shift drum is different, the ends are different for the different shifter arrangement. You can't just bolt one over to the other though because one is a pressed heat fit, the other is bolted and they are totally different arrangements. However you can use the old shift drum in the new block if you have a lathe handy, rollpins and some taps. You can lathe the end off, drill a hole then smack in a tiny rollpin to act as a locator. Also have to rollpin the centrepiece to stop it spinning and moving cause that's the press fit bit. I experimented with things. I had the newer shift drum and used that though, the tracks in the drums are otherwise the same as are the shift forks, I was just kind of tinkering. This also means they use a different bearing

The crank/spark pickup is in a different location, however you can't just move it back as the pickup points on the one way clutch for the starter are different, needs to be swapped to the old unit in order to use the old electrics.

The clutch cover is different, wouldn't be a problem except the newer one doesn't have space for the crank pickup in the alternate location so doesn't fit. The old one looks better anyway IMO.

Oil pumps, sump and pickups are different. They are interchangeable as a lot though, you could mod them to work in any combo but I had no need.




This little stuff ate a lot of time, I should stop being a cheap prick and just buy an already running motor lol. However I am learning a lot about assembling and working on these motors. I'm 100 fold better than when I started cause I know where all the little hidden bolts etc are. Hope it runs cause I can test it tomorrow maybe, well that's if it runs. The bike mechanic said you can get away with a lot though, just how much I'm going to find out. When in doubt use coppercoat or a hammer it seems.

[ducatilover]

Some really good info there

[328FTW]

Some really good info there

Oh but there's more



I put the motor in the bike last night, was a full all nighter. Used the new carbs on the old heads that are bolted to the new block which is using the old sump. The drilled and tapped oil feed lines, mismatched cams (used the newer ones, less marks on them), resused headgaskets and whatnot were all a bit of a worry. Lots of work for an unknown.

I was going to use the sparkplugs from the newer motor because it had been taken care of better and had new plugs. However the new heads use a different size thread for the plugs, so reused my old plugs for the time being. I spent HOURS trying to get spark from the motor. I checked everything and it all seemed fine, I got on the net using my smartphone and found an old article from VTR250.org. Guy was trying to put a VTR motor in his VT250F, he had the same problem and gave up on the old electrics which didn't give me much hope. However I read that he had spark but it was backfiring through the carbs, I had no spark period.

So after many hours the last thing to check was the VR sensor/crank pickup gap, I know from tuning my racecars it can be a prick of a problem. After bending the bracket slightly I got intermittent spark. Took about 4 more attempts but I eventually got the gap perfect and a steady crack-crack-crack from my test plug.

After all this I put fuel straight in the carbs from a can, full choke, hit the starter. Fired and died. Put the tank on and after some problems with a blocked fuel screen I had it running sweet. Just needs an idle adjustment. 5am ride in the rain on roads with tar bubbling through, was cracking the rear tyre all over the place once it hit about 9k in second. I'm pretty happy for 30 bucks though, the rear cylinder compression came up after a ride to, rings were a bit stuck from sitting.










And a quick vid of when I first started it with no exhaust, this was at 2:30 am this morning

http://youtu.be/mhyb51yt8no










Another thing to note is I had to cut my lower fairing. The gearshift sticks out lower, works out though because I have a decent sized foot and the placement is ok. The bike the new motor out of was an xelvis I think. Not too much newer but enough they are not perfectly the same. I think I used every tool in the whole workshop making this work. Shoulda put a VF400 motor in it then played dumb getting a WOF Also be interesting to look at a spada engine and the differences there.


Anyway I'm off to enjoy the spoils of my work because I damn well deserve it at this point I think.

[ducatilover]

Awesome! Do a skid?
The Xelvis is a beige version of the Spada unit AFAIK, 33hp or something (I like how the shit VT250 still makes as much as the latest 250 twins... )

[actungbaby]

[QUOTE=328FTW;1130405471]Oh but there's more



I put the motor in the bike last night, was a full all nighter. Used the new carbs on the old heads that are bolted to the new block which is using the old sump. The drilled and tapped oil feed lines, mismatched cams (used the newer ones, less marks on them), resused headgaskets and whatnot were all a bit of a worry. Lots of work for an unknown.

great work have you got a good spare bottom end i got 2 wreaked early vt motors

Both with shaged con rod bearings on the crank shafts, got price for getting welded 500.00

I will fix one of them when can get the money toghter as there sweet engine designs notiched even
The tapet lock nuts are smaller 8mm all for light weight i guess

[328FTW]

Lol it was short lived.

Of all the parts that failed it wasn't the $30 motor stuff at fault. I used my heads on the new block because of the smashed new head. Well lucky me they might of been a bit old n crusty, 13,000rpm on a downhill it dropped a valve. I heard a ting ting *fuck* KABOOM.

I kinda wanted it to last until I got the other motor ready with new bearings, new chains and all that stuff then swap them back and do the same again to the one on the stand. But we are talking total hand grenade here. Not the first time I've had hard work go down the drain but what are you gunna do?



I checked, the cam chains were still lined up right, the tensioners working fine, my clearances were checked when I had it apart, wasn't lean, plugs were healthy, bearings look perfect, fuel wasn't lawnmower 91 either. But being a cheap motor I didn't bother with valves or any other work. Was a pretty wild ride because I was caining the shit out of it when it happened and it blew the starter off the front of the block when the front rod let go, locked the rear and dumped oil everywhere. I'd rate it right up there as one of my best engine blows. Kept it upright though which I thought was not bad considering.

Kind of annoyed I couldn't find fault, normally I could pick something I fucked up but there was nothing that obvious. I triple checked the valve timing and chain setup cause it's pretty easy to get it wrong; did it all by the book even if I had coppercoated headgaskets lol. The rear cylinder was/is still fine and has compression, didn't make any weird noises apart from the ting of that valve I heard last second. Too late then anyway. Also not all the valves were bent either which kinda made me feel better it wasn't a chain skip issue.










It was also my birthday, up till that happened it was running really really sweet. Started first pop easy after I set the carbs up properly.

WTB: VT250 motor, preferably with headwork already done

[ducatilover]

Impressive! You deserve a beer

[bogan]

Brutal! Maybe not so many RPM on the downhills next time