Iceni

I should have done it already, The weather has been naff, and I've spent 3 days brush cutting scrub off allotments.... I'll try catch a window of oppertinity to get the test done in the next few days. It's typical that you say your going to do something then spend 3 days waiting for the rain and wind to clear I have no garage, so anything on the bike involves pulling off the covers and working in the back garden, That and the fact I don't actually ride it yet mean it's not always at the front of my mind.

The engine shouldn't be seized. Give it a fuel change, scrub the plugs, and charge the battery. Bet it starts.

Right I got my adapter this evening. I haven't been able to do a proper compression test yet as I didn't have time to warm the engine. On a cold engine I was getting 7bar from both cylinders. I'll do a proper test tomorrow on a hot engine. I'll also attempt to start the engine on 1 cylinder and get a running pressure. Stock mixture screw settings on mine are 2 3/4 out.

Cool, I've orderd a convertor for the compression tester I have should be here by friday. I'll make sure you get that information Oddly I was chatting to a friend today about his bike, and he was having a similar problem. Turns out when he rebuilt it he didn't know the pistons were supposed to be reasonably tight and thought that when they went in easy it was a good sign lol.

If the static compression test was as low as that I would ask them to do a Leakdown test. It's similar to the compression test. They put each cylinder at TDC then pressure the cylinder to a set value and see how long it takes to drop. I'll see if I can find my compression tester and do the test on my own engine. It's only done 2K miles so it should give you a decent comparison. The lower value of the compression test may be because the engine has valve overlap. Where valves are still open at the start of the compression stroke. I don't have the information about this engine to know if it runs with an overlap I would suspect it shouldn't. 5 bar is very low. Thats similar to the compression I would expect to see from a lawn mower engine. It's enough to run, But it's not optimising the thrust of the engine to get more pop out of the fuel. I also want to hear the results of the soapy water test. It's a very direct test and will give you a 100% problem to fix rather than the compression test that tell you that there is a problem somewhere in that region! Edit found my tester but it needs an adapter for the bike. It only has 18mm and 14mm fittings. As soon as i get the adapter I'll give you the readings.

On your compression test both cyliners should show about the same level of compression. A slight difference is common. You should see between 130 and 150 PSI on the meter depending on the engine. If the compression is lower than 125PSI then you need to look into the problem. A cold engine will also show more air leak than a hot one in most situations... Metal expands and closes the cylinder head gap a little.

No both of my cylinders sound the same. I think you should do a compression test for sure. Depends on the engine, On a single cylinder engine you should be able to rotate to the compression stroke then it will be almost impossible to roll past that going by hand. On the twin you should struggle to get it past the compression stroke on either cylinder. You have to remember that you have 2 compression strokes to deal with and you may get a false feeling if your on the wrong stroke. As for the air escaping from the timing cover, If the cover was open then you should be able to feel air escaping. This is normal as the pistons have an effect on the bottom of the engine as well as the top where combustion happens. That internal pressure should not be escaping Via the timing cover tho. It should be going out of the crank breather located at the back of cylinder 2. That noise should also not sound like compressed air. It should be more like a subwoofer pounding. If you can hear a hiss it is probably a faulty head gasket and the leak is not comming from the timing cover. You can test this with some soapy water, Put a good squirt of washing liquid in a bucket then brush the mixture on the engine with it running.... Bubbles are bad.

I've just been given an XV 125 and am pretty up to date on the forums for these bikes atm. Firstly I have no idea about the Irish XV restrictions. The UK model has none, But the Irish one may still have restriction in place set by Yamaha. Check your exhausts. There is a restrictor ring that may be in place. Check your Inlet splitter (rubber part under tha carb) the 125 has a rescticted inner. And check the seal on that part. A leaking manifold will cause you to run increasingly lean as the bike gains revs and pull more air. I take it you have picked up the power up guide available on another forum. It goes into detail about jetting, Carb settings and generally getting more from these engines. I suspect you have a problem with the engine if it revs freely but gives no power. I would sugest looking at your valves first. They may have weak springs, poor tappet adjustment, or have a seating issue. Your valves may not present themselves as a problem because the engine seems to be running well. But even a slight leak will cause the engine to loose a lot of the top end, whilst seeming good at the bottom end of the revs. You can test the valves using a cheap compression testing tool. http://www.amazon.co.uk/dp/B0001K9TV0/ref=asc_df_B0001K9TV013080721?smid=A3P5ROKL5A1OLE&tag=googlecouk06-21&linkCode=asn&creative=22206&creativeASIN=B0001K9TV0 I've already had my xv125 over 55MPH with a failure on the manifold. I'm a reasonably normal build 12 stone. Also how much added weight does the bike have. Boxes, sissy bars, chrome addons all slow the machine. The best after market addon is probably a fly screen. It'll keep the wind off your chest and reduce the wind resistance your own body gives I plan to add one to mine. Have you checked your rear sprocket? If for some reason that has been made larger it will reduce your top speed and give more acceleration. The previous owner already made adjustments to the front sprocket so checking the rear is a good plan. I think the standard rear is 47 teeth I'll count mine for you tomorrow.

It's no problem. I have one for the GW hobby I do, But it has been used on many things outside of the hobby, mainly laptop screws. Mine is like the steel one shown in the video. It'll take bits from 0.5mm to 4mm. The GW one only takes 1mm to 2mm drill bits. Your also going to snap a few bits. It takes some practice not to twist. The best advice is get a stool. Get comfortable, then use both hands and just go slow. One you have a hole thats 5mm deep you can start to try working the key into it. If they key won't fit just use the drill at varying angles and ream the hole till it goes in nice and snug, If you get it perfect then you won't even need to glue it as using the key at an angle should start to turn the screw.

The pin vice is the drill It's a palm drill. The end that sits in your palm rotates. You cup the pin vice in your palm, and rotate it with your fingers. The drill pressure comes from your arm. Like i said brass can be hard to drill but your not going to do any damage this way. As soon as you try and use it you will see how they work. Just make sure you turn it the correct way. If you get one from games workshop they will show you how to use it, The GW hobby uses it to put small pins into metal models so they don't fall apart when they get glued. This is a different application for the tool but it shows the grip well.

Because that screw is so small i would use a cheap allen key to remove it. Get a pin vice. http://www.anticsonline.co.uk/2413_1_10903.html and a 1mm drill bit. Very carefully drill the screw, clean out the swarf. Then superglue a 1mm allen key into the hole. Just use a very small amount of glue on the very tip of the key. You should then be able to unscrew it. Just take your time, Brass can be hard to drill. Don't be tempted to get the electric drill out tho as 1 slip could see you messing up that very soft alu casing or if the bit jams kill the carb threads. There is a Games Workshop on church street in Macclesfield. They should have this pin vice in stock and it comes with some tiny drill bits. http://www.games-workshop.com/gws/catalog/productDetail.jsp?catId=cat470006a&prodId=prod1095460

Did you get this fixed? I've had mine in bits this week. Is the gear shifter feeling the same when you change gear? It might be that you have slipped a quatergear up on the shifter linkage. Drop the oil. Remove the sideplate clutch and outer basket. At this point you should be able to see 2 quater gears on the shifter mechanism. Make sure they line up dot to dot. If those dots don't line up you'll have to take the oil pump slave gear off. It's a circlip. When you do this bung a rag in the sump drain under the shifter mechanism. I allmost lost a clip down that hole!

The intake splitter is ordered. Sorry for any Yam lovers that stick to OEM I went with a chinese variant Cost £11 delivered! It's the XV250 pipe with no flow restriction inside. I've got a mate heading over tomorrow. Were going to drive down to the local bits shop. See if they have any handlebars that I like. I'll want new grips as well as the stock Yam ones are a little ugly. I need a tank protector as well to hide some zip damage. Today i reset the jet position. The plugs are showing it to be running rich on both cylinders, But thats been at idle with one mild reving I was fully expecting it to be lean with the split in the pipe. Once I have this part and I can take it down the lane and get some heat in it I'll make sure it's running brown. I also had a little power test earlier and managed to get the back wheel spinning on the grass in my back garden I've also reset the brakes. The rear brake pedal was set at a silly angle. So it's been dropped to be inline with the shifter. And I've sorted the play on the pedal so it comes on when i want it to rather than when you tap it! I also found out I can get to the tool box without needing to remove the seat. This means I won't have to carry a set of spanners in my pocket if i want to adjust on the fly. The last part I need is the sealing washer on the sump bolt. Mines got a little drip of oil (3 drops last night). Looks like I'm running out of excuses for not going and doing a CBT! .

I'm not sure. As far as i know the block has never been stripped so I don't think it's a bad mechanic. Perhaps it happened in the drop. The shift might have been landed on causing it to jump a tooth. The odd thing is I got the impression the previous owner had ridden the bike after the drop. I know the drop happened before I had even met him and that means if that is the case then it's been sat unused for over 8 years, with only a minor fault. Some people must have money to burn to leave a simple problem that long! I've also found a few more issues with the bike. The main one been a small crack forming in the rubber inlet manifold. I want to strip the carb at some point as well so I think i will replace this part with the strip down. I'm not sure if i can remove the carb without removing the tank. I'll so some digging and find out. If i can it should be a fairly easy job. I'll clean the jets, do the float tank then rebuild it to factory standards. I may also pick up a larger jet kit at some point so i need to know what the carb is like to remove. I think the tappets want doing as well so there is plenty to be doing. I've also decided that the sissy bar is going to go. I may get it stripped so i can put it back on at some point. It is the only bit of the bike other than the handle bars that I hate. The handle bars are also going to be replaced. There for want of a better word uncomfortable. They put my wrists at a funny angle so I will be replacing the whole bar with something lower and straighter. The bars are also slightly bent and I need new end caps. So a full replacement will work pretty well. I'm also thinking about adding a screen. Nothing big or fancy, Just a little wind reflector. It should help with the top speed, and improve fuel economy slightly. I'm going to keep an eye out for something that suits my needs. By the end it's going to end up looking half way towards a cafe racer lol!

I just stripped it this afternoon, Took off the clutch down to the spline, and the oil pump gearing so i could get into the gear selector. Turns out this bike was incorrectly put back together at some point. Part of the selector mechanism wasn't lined up dot to dot. I moved it over 1 tooth and it now selects all gears... so simple. LOL. The gear selector is not like the xv535 or xv1100 setups. On the selector arm you have the pawl, spring and quatergear. It also has an extended shaft with the oil pump gear sitting on the end. The quater gear links to the cam follower and arrestor on the LHS of the gear drum. The Quater gears line up dot to dot, thats where the problem was. The effect on the pawl was to place it lower than it should have been on the drum. Causing it to miss the upshift nubbin. I'm not sure why neurtal was still working TBF