Thunderchild

Back to my problem. I've tested the resistance on my TPS: blue/black = 5.30 (service manual 4.0 - 6.0), so that's fine. yellow/black = 910 - 4.17 (service manual 520 - 900 to 4.0 - 6.0), for opening throttle. Although it was a gradual increase on the second test, my starting position of 910 ohms was higher than the upper recommended limit of 400 - 900! Does that mean the TPS has had it? I know you can adjust it, but I've read that it rarely works anyway and is easier to replace. What do we think? Is this the cause of my original problems for lack of acceleration?

This is a place I bookmarked for when I need to get some accessories, they seem to have loads of stuff. http://www.metriccruisers.co.uk/acatalog/yamaha_xvs125_dragstar_accessories.html

I only ever found digital copies online for about £15 when I was looking for one.

Does it have a TPS (Throttle Position Sensor), on the carb? I have one on my XVS 125. If it's faulty, it could be causing the engine idle speed to increase. You could check it (if it has one), by following the manual or this video shows you a generic carb test.

edit

I'm waiting for my multimeter to come back this w'end before I can test it. It's looking like a possibility though atm Airhead.

Paul/Airhead thanks for getting back, I've just checked the new plugs again and despite only having the bike idle or taking it 200 meters down the road a couple of times to test it, they both have very heavy black carbonisation (dry), on them. Could this be a weak ignition or do I need a new air filter instead of just cleaning it? It could be the ignition timing is retarded to far I suppose. As for the carb, I followed the manual to strip and reassemble, and cleaned it with carb cleaner. To be honest, it was pretty clean anyway and none of the jets appeared to be blocked.

As per my other posts, I've still not managed to get my XVS 125 going and missing the summer sun : ( Having gone through various 'causes' of her problem, she is now back together and starts up fine. Whilst idling, she sounds like she is wobbling slightly instead of a steady tone. I have just taken her for a spin and I'm still struggling to get out of first gear before she cuts out completely. Things I've done so far: Changed plugs, oil and oil filter. Cleaned out air filter. Checked throttle cable. Removed tank and checked fuel lines and petcock. Sealed the silencer carb junction with gasket seal. Sealed cracks in carb manifold (very minor), with gasket seal. Removed carb, stripped, checked, cleaned out and put back together. She originally died one afternoon whilst out on her and limped her back doing 15mph. Not been able to fix her since. There is no oil leaks and fuel appears to be flowing into and out of petcock. She is not smoking from the exhaust (so I don't think it's the rings but may I be wrong?). I've not checked compression as I haven't got a gauge yet. She doesn't cut out whilst idling (just sounds slightly wobbly). Any other ideas? Any advice better than taking it to the garage. Cheers.

Well I've put some gasket sealer on the split to see if that helps. I've also put some on the carb manifold splits that didn't look that bad, but just to rule it out. Now for the carb clean.

So for those that have read my other posts, I've been having trouble with bogging and not been able to get over 15mph on my XVS 125. I've just removed the silencer to get to the carb and noticed this: That is the underside of the silencer that connects to the top of the carb. In the fragile diaphragm around the junction are two clearly visible splits. Can this be sealed again and is it related to the bogging? Cheers.

She starts no problem Paul, just bogging and not go over 15mph. I was going to clean out the carb today but once I found the oil in the air filter again I stopped, which is why I thought it could be the rings. I guess you could be right about the oil in pipes, as she is not blowing smoke when she starts which is what made me indecisive about the rings now. I'll have a look at the engine case breather and see what's happening. If she looks ok, I'll go for the fuels lines check and then clean out the carb. Edit: Just checked the breather and it's fine, no oil whatsoever.

She has new plugs, new oil and filter. It was the first place I started as she had had too much oil in her to start with, so she's not 'over filled' any more. I know to expect a mist of oil in the air filter, but this was a small pool in the bottom of the case. I only cleaned this out recently so there shouldn't be that build up already from a quick test ride down the road. That's why I'm thinking the loss of compression is causing the bogging and blow through of oil. I'm waiting on a compression test kit coming to be sure before I spend out on a new set of rings.

I'm now thinking either bad compression ring, head gasket, or valve guide problem is causing this. Since she's bogging too, I'm guessing compression ring. Would you agree?

Closer look, the oil seems to be coming down the silencer into the back of the filter as the silencer is wet inside.

I've been having trouble with bogging on my xvs 125 as can be seen in my other thread. I decided today to clean out the carb and noticed a pool of oil in air filter again. I recently cleaned out the air filter and also changed the oil and oil filter so it's not over filled. Is this the piston rings or the crankcase vent tube? I can't see where it has come from to be honest and it's not smoking when started which I would have thought would be an indicator of the rings? She did have too much oil in her previously which is why I drained/changed it all recently. She felt like she wanted to go yesterday when I tried her, but bogged down again and cut out when I stopped. Any ideas welcome.

Having had trouble starting her up, she finally started this morning and I took her for a spin. Having cleaned out the air filter, she is still bogging but nowhere near as bad as before and actually feels like she wants to go but can't. Since I now have a workshop manual, subject to weather, I'll be cleaning out the carb this weekend and checking the fuel lines.

Thanks for the reply. All checked and she now starts again. Just took her for a spin and she's still bogging, but feels like she wants to go. Back to checking the fuel lines and cleaning the carb out I think.

I've had another look at her today and she's still only turning over but not firing up. I'm now stumped as what to do next

Last night she started fine but was still bogging when I applied throttle in neutral. So since she is still bogging and having gone through various things, I decided to clean out the carb today. I removed the seat and speedo, but when I came to remove the air filter, I noticed there was a lot of oil in it (she had previously had too much in it to start with). I recently changed the oil, plugs and oil filter but had forgotten to check the air filter. So I've now clean out the excessive oil, cleaned the filter and put the unit back together. I reconnected the small hose and silencer and fitted the air filter unit back onto the bike. I reconnected the speedo, two sockets and cable at both ends, then fitted the speedo unit back to the bike. Now when I tried to start her up, she will turn over but not fire up. Have I blown something whilst working on her? I don't see what I could have done, since she started fine yesterday Any ideas?

Thanks for all the feedback. I've been working my way through your suggestions (in between rain and work), and have decided to strip the carb and clean it out. So, I'm ok taking everything off to get to the actual carb, but I've never removed one of these before and it seems to have lots of cables and pipes (I say lots, more than I thought it should have). Other than photographing everything before I start and during, can anyone offer advice about removal and cleaning the carb before I go any further? I think the only way to learn is to do it and I'd rather learn than pay a mechanic to do it for me. Cheers in advance : )

I like Guildford, I once lived in Weybridge and had friends over there. New here too, so welcome : )

I went to college in Wigan, many years ago. The new building on the other side of the park, not the main one with the wheel outside.

Indeed drewpy, my first ever vinyl when I was a kid

Dirty, I've been to MB a couple of times, but I find the ride in better than the arrival Paul, I'm right on the border between Derbyshire and Nottinghamshire, not that far from the M1. Blackhat, I have friends that go to MFN on a Wednesday (?), but from the photos I've seen, I'll wait until I get a bigger bike. Don't want to turn up on my little 125 with friends on Wings and 650's. Not that I could keep up with them Thanks for the welcome : )

Just a quick hello from Derbyshire. I ride a Dragstar 125 at the moment and have been for about 16 months. Having gained the road experience on a bike (been driving for 20 years), I'm now looking forward to doing my DAS this summer so I can upgrade to a big boys bike. Enjoying the ride, but now have cc envy. That said, arriving at school on any bike (I'm a teacher), still gives a certain degree of kudos with the kids. Ride safe.