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Discussion Starter · #1 ·
Hi guys,

A few days ago I started on my XV920 that I recently bought. Its my first time working on a bike so it's a little overwhelming but so far it's going alright. I opened up the left side of the engine because it didnt start and the starter wasn't sounding healthy.
As expected the starter gear looks pretty worn down so I'll flip that around and see if that makes a difference. But I also came across this.
Wheel Automotive tire Gear Tire Motor vehicle
The stator coils seem to have some wear on them. I'm thinking this would render it useless because the coils are touching now but I honestly don't know. Also I have not a single clue how it would have worn like this. Any suggestions?

All help will be massively appreciated.馃檹
 

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Discussion Starter · #2 ·
Also, here is a picture of the other side.
Automotive tire Motor vehicle Rim Stairs Circle

it also looks like the bolts on the stator have somehow created a bit of wear on this part. But it's still not very obvious to me what wore down the stator.
 

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The XV starter system is a bit of a disaster, you need to find service bulletins for the 'upgrade' parts (basically the drag spring on gear is very weak)
The first one we sold at dealers was so bad I pulled cover off to find out what was wrong while general manager was calling Yamaha to get some info. Yamaha said, 'It's completely normal' (then sent out service bulletins and replacement parts)
It was a very popular motor in Europe for sidecar motocross (which tends to be a bit spectacular when things go wrong)
I don't know how much tuning information is available but I do remember riding one converted to 1100cc with a lot of 'fast bits' inside.
It was about as scary as a Suzuki RG500 and probably around the same power output (~115bhp)
May not sound like much today but in mid 1980's before suspension and frame technology had caught up with engine development it was fast
 
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OH, your original question, the Allen Head bolts look like replacements with a taller head, possible wrong gasket fitted to cover as well, need OEM gasket to get correct clearances
 

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Discussion Starter · #5 ·
Hi crazypj

Yea I've heard a lot of stories like that. That's also why one of the first things I wanted to do is check out the starter.
After some more searching I've come to find out that there is quite a bit more going on inside of there. There's are a few pieces of the flywheel magnets that look like they've broken off or something like that.
Motor vehicle Automotive tire Wood Material property Gas

Also it seems like someone has already modified the cover to give the starter more space. I know there is a local motor shop that does these starter-modifications so I'll be calling them tomorrow to see if they can give me some information about it. Here's a photo of what's been milled away.
Automotive tire Bicycle part Automotive design Rim Motor vehicle



I'll update soon!馃槄
 

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It rock solid. Doesnt move one bit. Ofocurse it turns but no wobble or anything.
if its the bearing , when and if you get it running . a couple of thousand revs it will wobble and youll know. what side of the engine is the ignition/ pick ups on? same as stator? check them for damage.
 
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imho I think you're likely to need two: 6308 deep groove bearings 40 x 90 x 23mm and if you have to split the engine casings you might as well change the bearings with quality brand units for a cost of about 40 bucks each. Difference between a quality bearing and a cheaper one is the number of balls in the race, I would roll with SKF.
 

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We鈥檙e the dowel pins in place between the stator cover and the engine case?
 

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Discussion Starter · #16 ·
Hi guys, sorry I been away for a bit.
Thanks for all the information. I've tried to check a few things you've mentioned but I couldn't find anything wrong with the bearings or the rotor and I wasn't planning to split the engine just yet. I don't want to get in over my head just yet so I decided to focus on the starter gear, make sure there's no debris anywhere and close it back up.
I tried to start it and 3 out of 4 tries it turned without any noise and only once the starter didn't engage but it didnt make any awful grinding noises. 馃槂 compression is on the low side but I've got a full gasket kit although I want to try and get it to fire/idle before putting all my effort into rebuilding the engine.
 

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Discussion Starter · #17 ·
It runs!!

I had some issues with the carbs flooding but i adjusted the floats and it runs great now.

Ive started to dissabsemble the rest of the bike now, starting with the swingarm. I want to run a atleast a 150 in the back but the driveshaft seems to be very close to the center of the bike so im pretty sure the wheel will end up slightly off center.
Ive read a lot of threads saying that thats okay because the bmw k-series bikes have sports versions where they have a bigger wheel but no other changes so they are also out of center.. so if its factory it should be fine and you shouldnt notice it. But i also read that people notice and actualy feel its uncomfortable to ride because of the 'pull to the right' issue on those bikes..

Not sure what to do. I really want 150 馃槄.
Let me know
 

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If your question is: can you have your rear wheel offset to one side compared to the track of the front wheel :unsure: well No that's not going to work so good as it will certainly compromise your steering in both directions.
I have a BMW K100RS and the rear wheel follows the front wheel accurately. If I was to install an over-size tire on that bike the centre of the rim will not change unless I put a thick spacer between the rim and hub which would be a very bad idea if the motorcycle is going to be ridden, if you are building a motorcycle just to look at that might work.

... BMW K bike crankshaft spins in the opposite direction to the transmission and alternator and the purpose of that design is to prevent the inertial 'pull' to the right which is inherent to older longitudinal layout engines, K bikes do Not have the inertial pull to the right on hard acceleration.
 

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Discussion Starter · #19 ·
Ah okay thanks i did not know that about the K bikes.

Im also quite sure that the rim being off center would impact handling. Yet ive seen quite a lot of builders especialy of viragos that have changed the rear wheel so they can fit a bigger tire with it being slightly off track (+-9mm or so). I obviously have no idea howoften they ride it or if its just for show.

Its something i have to keep researching for now. I do really want my bike to be straight...
 
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