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4 Stroke Single Engine Rebuild


ferg

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Evening gentlemen and kind lady folk. This summer my XT had an embarrassing moment and I now have to go about mopping up after it. I've sent the (incredibly lonnnngggg) email below to Slipstream Racing and David Lambeth. Have heard back from Slipstream but nothing yet from David who runs Rally and Overland. What are your opinions on the issues and thoughts on fixes and people do do such fixings? Ideally I'm looking for recommendations of firms and opinions on work that I should have carried out. If you manage to read all this and the email below please before you fall asleep add your thoughts.

Here's a picture of the steed to thank you for getting this far so far...

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The email went something like this:

"Secondly my bike is a bit poorly. The engine tried to dump all its oil from, I think, the oil filter cover. The threads have deteriorated and I think (again) haven’t now got enough of a hold when the engine gets up to temperature.

Do the bolts for the oil filter cover go directly into the cases?

How would a repair work? Could new threads be cut or would a helicoil or similar be used?

I managed to get the bike stopped and switched off with there still being half the oil left in the bike. Hopefully this means that it hasn't been starved of any lubrication. The ‘red arrows’ display happened unsurprisingly after an oil change and prior to the plumes of white smoke the bike was running very nicely.

Additionally to that the engine was previously using a bit of oil (to the point when filling with oil in Ullapool a guy asked if it was a 2 stroke!). It was noticeable from friends following when rolling on for overtakes that there was oil being burnt. The engine is on forty thousand miles now and has had a number of owners prior to me so it’s expected to be a bit worn and tired but this latest issue seems to offer an opportunity to get things back to a better point.

Also (this is beginning to sound awful for the poor bike) there's a noise from 5th gear. I've read that you shouldn't use 5th to chug around on but anything below 65 mph and you get a whine as if it's not very happy at all. So I don't. My dad's bike doesn't do this yet mine has since the day I got it. If the engine was being stripped or partially stripped, would it be worth while to have this investigated also?

I use the bike for everything; from normal day to day riding, to touring to off road work. The bike has been brilliantly reliable and quite frugal giving back around the 50 mpg mark. I would like it to keep the ‘jack of all trades’ nature and hold on to the reliability and reasonable frugality. However I’d also like it to feel a bit fitter and have a bit more pep. I know it should be reasonably keen to lift the front but at the moment, or rather previously, it takes a lot of persuasion!

What would you suggest to do on these (many) points? The bike is a keeper and will never be sold so I don’t mind spending a bit on it. Yet only in the interest of making it better in all areas without detracting from any other. It is also currently wearing a full Devil exhaust system if that makes any odds too."

Like I said a rather long email.

Have another picture as way of an apology...

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Buy a manual & do it yourself & it will then be done right & you will have saved a few bob.

Singles are the easiest things in the world to work on & there is not much you can do wrong.

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Definately do it yourself.

As long as you take loads of pictures and bag everything up.

Make cardboard templates of mounting holes or engine covers and poke the bolts through so you know which bolt comes frim where.

Also there's plenty of help available on here.

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Definately do it yourself.

As long as you take loads of pictures and bag everything up.

Make cardboard templates of mounting holes or engine covers and poke the bolts through so you know which bolt comes frim where.

Also there's plenty of help available on here.

^^^^very much this^^^^^

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Hmmm.... to be honest I hadn't thought of doing it myself. Will do bits and bobs but an engine rebuild seems like a big step. There's an issue of no manual for XT's of this vintage and there would be bits that I definitely couldn't do myself however like the rebore (if it needs one I suppose). Time would be a major issue, half way through primary teaching probationary year but I will have two weeks come Easter..... feck you guys have got me thinking now.

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Hmmm.... to be honest I hadn't thought of doing it myself. Will do bits and bobs but an engine rebuild seems like a big step. There's an issue of no manual for XT's of this vintage and there would be bits that I definitely couldn't do myself however like the rebore (if it needs one I suppose). Time would be a major issue, half way through primary teaching probationary year but I will have two weeks come Easter..... feck you guys have got me thinking now.

I recently re-built an R1 gearbox and also did the valve clearances, I'd never done either before, prior to that I'd only ever done basic servicing and bolting on bits.

(ok, I admit my Dad and me (ie my dad did them with me getting in the way) did the valve clearances on an old mini once or twice, many moons ago, so I at least had a basic idea of what was involved)

I was worried it was too big a step but provided you can tell one end of a hammer from the other you should be fine. I learnt a huge amount along the way and got a massive amount of satisfaction along the way from doing it myself.

as others have said a single is about as simple as it gets four-stroke wise so I would say get stuck in!!

there's a massive amount of help and support available on here.

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Just done my XT350, top end rebuild, it is rather easy to do following the manual(clymer in my case) and there is help out there, especially thumpertalk and advrider. If its just the oil filler cover then use helicoils(or similar), the originals are very soft and nearly stripped mine

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Just do it your self. It may seem like a big step but honestly its not. Its just a different shapes jigsaw with a few more bits. Think about it, research it, plan it,be prepared to walk away from it when you feel its not going right, and ask other people the questions you don't know the answers to. Time and confidence are all you need. Besides its bloody good fun and the feeling at the end is well worth it!

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Plus one for doing it yourself.

Be prepared to buy any specific tools you might require; flywheel puller/holder, clutch holder, etc. If you can't buy it then make it(if you can, obviously). I learnt this the hard way trying to make do with what I already had.

If you decide not to do it yourself give Martin Wittering at Torque racing a call. He offers a collect and return service, if I remember correctly, if you're too far away.

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Cheers for the comments guys. Slipstream gave me a list of suggestions for the engine and a ball park guide to figures. Adding it up last night came to a scary sum of around £1300. I realise Slipstream are incredibly good at what they do and are more used to building racing mono engines but I don't think I can justify spending money like that on a bike that although I will keep forever, only cost £400!

They have suggested:

A 102mm bore. The bike has been burning oil when rolling on the throttle. That normally hints at oil getting past the rings doesn't it? If so I could see the sense in improving rather than just replacing with standard. But will it need it? Would new rings and a rehone possibly suffice? Will I have no idea until the head comes off?

A gas flow and a new cam. This is obviously more along the lines of proper tuning rather than fixing. I like the idea but if I was to rebuild it I could still send the head off for some work I suppose.

I've the engine out of our old Honda XR75 that needs split to replace the kickstart shaft. Would it be worth while having a practice on this or should I (if I go down the diy route) suck it up, figure out what I want to do, order parts and needed tools and get stuck in?

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I'm one of those annoying people who finds it helpful to write things down. Writing the above down and having a further ponder has left me thinking that the main thing I need to sort is the oil filter cover screws. Get them sorted and the bike will run. From there I can worry about further rebuilds and extra work. How easy is it to mess up a helicoil insert though? As it's straight into the cases it will be a bit of a bugger if it goes wrong...

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DIY and spend 300 on tools. That way you get sexual satisfaction as part of the deal. Oops

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How easy is it to mess up a helicoil insert though? As it's straight into the cases it will be a bit of a bugger if it goes wrong...

Just be patient and slow while doing it and you'll be fine. Careful with the drill, careful with the tap and the rest is a walk in the park.

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I'd also suggest using a solid insert such as a timesert rather than a helicoil. They're (imho) a much better permanent solution especially if its something you're going to be removing periodically.

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I've heard people recommending Time Serts over Helicoils before. What is the difference between them? If I wasn't to do it myself, with herr faither looking over my shoulder or vice versa, would it be easier to do with the engine in the bike or with the engine out?

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  • 2 months later...

Coming back to this. I managed to get a hold of David Lambeth who runs/is Rally and Overland who specialise in XTs. He chatted me through a few things. The whine that I'm getting is very common and is wear to the 5th gear; which means there are bits of said 5th gear floating around in the engine. Which is nice. The whine is the beginning and it develops into a vibration which you can feel through the pegs while riding.

When he rebuilds an engine he machines bits and bobs here and there and uprates certain components. He has a few bikes in at the moment and one that he rebuilt ten years ago for an overland trip. The bike has now covered 100k miles and is in great condition after the strip. He's replacing bits as he has it apart rather than because they are needing replaced.

He reckons the bigger piston and gas flow etc is pointless. Unless you're going the whole hog and building an engine for 65 bhp the small improvements won't really be felt. A rebuild takes him a minimum of 20 hours and just in labour would cost £700.... with parts that would probably be around £1200, which is obviously a guess.

I'd love him to rebuild my engine as I know he'd make a fantastic job but I really can't justify that sort of cash at the moment. So back to the homebrewed idea. I won't be able to do the same job as he could do but having a go myself shouldn't cost £1200! With the changing of at least 5th gear am I going to be swimming into ever deeper water?

Possible start during the summer holidays as the garage should be reasonably set up by then and the Easter holidays have been taken up by Fireblade :)

Any words of wisdom or advice?

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Why not take the engine out, strip the top end yourself, remove the engine side covers and then let David sort the oil filter cover bolts and the 5th gear? Be a lot cheaper that way too.

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That's an idea. I'll give him a shout and see how much that would/could knock the price down by. When I asked about him supplying parts for me to do it, there was a simple "no" due to previous bad experiences but that may be a good enough compromise.

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I've got a factory manual for the XT, although it's a 2003 one and is for the electric start they're pretty much exactly the same. Let me know if you want it and I'll see if I can get it to you somehow (it's on my old computer and had a crappy demo version of adobe but I'm sure it can be sorted).

I would agree with the comment of forget the tuning unless you're going the whole hog, anyway you've got a blade now for silly power! Go for the rebuild yourself (if that's what you decide to do), I'm entirely self taught and you only learn by getting stuck in, but give yourself the whole summer holidays to do it because with a bike that isn't common as muck there's always something that you find and need to order half way through that'll hold you up.

I can't remember which bit they changed to solve the 5th gear issue on later models (it was really common on the older ones) but they basically improved the oil flow onto 5th. That would be the one thing I'd look into having someone else do due to the machining involved (unless it needs a rebore, but I doubt that from what you've said, rings and a hone should be fine but you won't know until it's apart), because it will make the engine a lot more reliable in the long run if it's a keeper; but I would just send the parts that needed machining and save loads of cash by stripping it yourself.

Don't be scared of the thread repair and you should be able to do that bit with the engine in the frame because there's quite good access. Although it shouldn't cost much or take long to have a local mechanic/engineering place sort it for you if you don't trust yourself, plus you can suss out if they'd be any help if you get stuck during a rebuild, it's great having somewhere local to pop over and pick their brains.

If like in your last post you decide to just do the top end then that won't be a drama and you should go for it. But a gearbox isn't as complex as you'd think, just be very careful with marking stuff as you take it apart and take loads of photos (a permanent marker or tip ex pen is you're friend!).

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Do it yourself with a good manuals and the right tools.

A drill press (IMO) to redo the thread repair so you get a perfect straight hole,no good on the pi**.

Just do bit by bit and if you get stuck theres loads of help on here.. Burntout came over to learn how the gearbox went back together on his track bike as he had no idea..We all had to learn at some point. As they say knowledge is power. :icon_salut:

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