Good mechanic for DT or 2 strokes in general

  • Hello,

    I do a lot of work on my DT myself, but I don't trust myself with certain things.

    Is anyone able to recommend a good mechanic to take a DT to. My local guys seem a little scared of 2 strokes in general. Preferably somewhere in London, but honestly, I'll ride pretty far to get good work done.

  • Global Moderator

    What tasks don't you trust yourself with? For me, I've never attempted fork seals so that's my current wall in terms of maintenance. Apart from that, rear gas shocks seem a bit scary.

  • I generally avoid anything to do with actual engine internals. I'm by no means an expert, but I understand the fuel and the air, the carb then down to the reeds, after that I have no idea until the exhaust comes into play.
    I know some stuff happens with a piston and a cam. I think there's also something called a flywheel, then all this stuff starts moving when I kick the thing?!

    not much else on the bike puts me off, although I can't say I've ever attempted fork seals on a motorbike. I used to service my bicycle rear gas shock, presumably the same principle, but maybe not.

  • Alright buddy, what was it you were after having done. PRetty incompetent mechanic if refuses to work on 2 Strokes given how simple they are.

    No cams on two strokes mate. The intake and exhaust ports are operated by the piston skirt abd head. Transfew ports get filled up with a combustible mixture after it has been compressed inside the crank journals. They then get drawn up into the combustion chamber as the exhausts gases causes a vacuum and the exhaust pipe creates a pressure wave that forces lost fuel air charge back into the combustion chamber.

    There is a little more detail tha that but thats the jist.

    Plenty of help on this forum could do it yourself no problems. Sounds like you have done more technical stuff.

  • Global Moderator

    I find diagrams like this one invaluable in terms of understanding how different engines work.

    you have to imagine the fuel coming in from the opposite side to relate it to bikes but its virtually the same.

    There is also a similar GIF on this website along with a brief outline of how they work.

    It's really a case of taking it bit by bit. Start with something simple, like taking the clutch cover off, and perhaps checking the clutch basket for wear. Once you have achieved this you could try stripping the bikes plastics and tank to give you a much better look at the engine. From there, try taking off the head and the exhaust and have a good look at the piston. When you feel you have hit your limit, put the bike back together and start again another day. I find the best way of learning is through experience. Although it is always handy to read up before hand. Get the correct tools and maybe a Haynes manual and you'll be fine.

  • Basically I'm looking for what's usually labeled as a "rebuid" service.

    A few months ago I got a lot of water in my engine, I assume through the fuel tank. The bike was running strangely and it still had the fuel that I bought it with so I drained the petrol tank and found it was about 10% water.

    New fuel and some hard riding got the engine feeling normal again, but I'm concerned that water in the engine could have caused some problems I don't yet know about.

    I'm looking for someone to strip the engine from the bike, take the engine apart, have a look see and tell me if it's okay or not. It's more for piece of mind than anything, but I'm planning some long trips on the bike so I don't want anything dying on me in the middle of no-where. It also seems like the sensible thing to do before I start looking into derestricting everything for some more power.

    Maybe my fear is irrational, opinions are welcome.

  • @MIGHTYMAN Thanks for that, that actually makes it seem very simple.

  • Global Moderator

    In your opinion, does the bike SOUND okay? One of the reasons I love two stroke bikes is the fact that you can diagnose some of the major engine problems just by listening. If your unsure, upload a video of it starting, idling and revving and we will take a listen. Not saying we will be able to diagnose something for sure, but if you have a good enough microphone on your phones camera, it might be useful. If for nothing else, then to act as a comparison for when you do get your engine refreshed.

  • Personally, I think the engine sounds pretty rough if I'm honest.

    I have a kick start on the RE motor. I know kickstarts can make some noise. Holding the kick start firmly doesn't make the sound stop though.

    It only sounds rough at low RPM, when I rev it, it sounds perfect. That could just be that the bad sounds a drowned out though.
    I'll try record what I'm talking about when I go out tomorrow.

    It's also really not easy to start at all. Sometimes I have to give a good 20 - 30 kicks. Thismorning I had to roll start it.

    While I'm listing problems with my engine, here is one I'm less worried about. It also doesn't idle when cold sometimes. I've been riding it really hard lately (This seems to be fixing problems?) and that problem seems to almost be fixed, but every now and then it cuts out when it should idle. Turning the idle screw higher can make the bike a little crazy, sometimes reving high when I'm stopped. Even when the idle screw is like that though, it still sometimes wont want to idle. So, I have it idle very low to prevent the out of control engine thing. I'm happy to give it some revs at the lights if I need to, as long as I'm controlling it.

  • @MIGHTYMAN said in Good mechanic for DT or 2 strokes in general:

    In your opinion, does the bike SOUND okay? One of the reasons I love two stroke bikes is the fact that you can diagnose some of the major engine problems just by listening. If your unsure, upload a video of it starting, idling and revving and we will take a listen. Not saying we will be able to diagnose something for sure, but if you have a good enough microphone on your phones camera, it might be useful. If for nothing else, then to act as a comparison for when you do get your engine refreshed.

    This is true for most engines. If it sounds like it has got dsound in the engine then it's probably time for a rebuild. Fresh engines will have a nice little whistle to them. Will start on the dime and will idle perfectly.

    To be fair, water ain't that much of a killer unless you're talking about hydrolocking.

    In fact it's common to see people Water inject engine.

    Water slows down the combustion propagation of fuel, thus you can run greater advance without the risk of detonation. This also allows you to run higher boost pressures on lower octane fuels.

    So the fact there was water in the fuel, ain't really that bad. The thing it will do is damage seals. The engine is Aluminium, so it isn't going to rot like Iron. The sleeve is iron, but that should be well coated with two stroke to inhibit rust.

    If you're having the cases split, for the sake of £100 puit all new bearings in.

  • @Uber_Beluga My RE won't start without choke. Or at least it didn't on the original.

    Had be scratching my head for ages. Would literally only start on the bump. Quickly realised that it always needed choke and that was that.

    On the kick start mechanism, there is an idle gear that connects the clutch basket to the kick start. This can have a fair few millimeters play in it which will give a distinct rattle. It'll want some new thrust washers on it, but there is no load so it's not imperitive.

    Two strokes rattle anyway, it's the name of the game.

  • Global Moderator

    I think the lack of idling and poor starting could be down to poor compression. Maintenance on two stroke engines does require replacing the piston and rings every so often.

  • Yeah, I've never been able to start the bike without choke, not a chance unless it's very warm (Just turned off after riding for long)

    Well, my bike it currently parked a couple of miles away in town as I actually couldn't get it started, first time It's been that bad in a long time.
    Then again started up first kick thismorning when I rode. I think I've wet the spark plug from trying too many times, going to leave it a few hours then go back and try again.

    Driving me crazy now, I love my DT, but it's just not something I'm able to rely on. I'm currently looking through 4 strokes on Gumtree, but nothing is taking my fancy.

    Any ideas for a good mechanic I could get the DT to and have them sort out my engine problems? I'm happy to pay for a new piston and rings, or whatever she needs really.
    Failing that, I guess it's time to start taking apart.

    Maybe I should just buy another DT, this one started first kick when I got it though so who's to say I won't have more problems. It's a very sad day 😞

  • Global Moderator

    Very simply start would be to change the spark plug out for a new one. Definitely something you'll want to buy if your having work done to the engine anyway so might as well try it first.

  • I swapped the plug out when I bought it actually, I guess I could do it again.

    What do you guys think about this place:
    They are reasonably close. I know there's not much you can tell from a website. How much do you think a rebuild should cost?

    Their given address is just a residential house, not very confidence inspiring.

  • Global Moderator

    I would be very wary going to a company like that. A friend of mine sent of a YZ125 cylinder to a company similar and he later found on a forum somewhere that most people didn't receive theirs back. I know someone in Dartford who is very good, runs a car garage but also services, repairs, rebuilds and also races two strokes in his spare time. Any bits I need doing I take to him. He charged me £120 labour for a full rebuild on a KTM 125 engine. Main bearings, full oil seal kit, gasket set, conrod and piston I had replaced. I handed him the engine and the parts and within a couple of weeks I collected it. He does get busy mind. Are you willing to travel to Dartford? Also, how long are you prepared to wait for the work to be finished?

  • Well, good news is that I managed to get her started on my second roll/bump start attempt.
    Bad news is, kicking doesn't seem to work at all anymore. Maybe this is a slightly more urgent issue for another thread, I'll make a separate one.

    Your guy sounds perfect in the long run though. I need the bike for a ride to Leicester in August, but otherwise I can wait as long as it takes.
    Dartford is a treck, especially without my bike and carrying an engine through the tube and trains, but it's worth it for good work
    Do you have any contact information for the garage or the guy who does it?
    I'll need to do all this next month after I get my salary as I'll need to order all these parts as well, I'm happy to replace anything that can be replaced assuming it doesn't become absurdly expensive.

    If you ordered the parts prior to taking your engine in, where did you order them from? Did you select parts based on problems you had or just replace everything you could?

    Altertnatively the guy at that racoon 2 stroke place has quoted an estimated 500 for the rebuild & 90 fitting fee to strip and re-fit the engine. It's 2/3 of what I paid for the bike, but it is a really tempting option.

  • Global Moderator

    I was wondering how you would go about getting to and from the garage. Lugging a DT engine around on the tube is mad! In the past I have usually just given him the engine first, then he tells me what to buy, and I drop of the parts after. Not really the best option for you.

    I still would look around a bit more and even get it done at a reputable bike garage if your willing to pay £590. Although if the Racoon 2 stroke company is as good your hoping, I'm sure they won't mind you enquiring and going to have a look around at how much work they get and whether or not they are using high quality tools.

    Otherwise if you are able to post the engine, I think Calum is / was offering a rebuild service a while back. Is that still a thing Calum?

  • I can rebuild the engine no worries. Depending on how extensive you want the rebuild depends on the price.

    My only concern is that I wouldn't be convinced that this is solely a worn engine problem.

    Happy to rebuild the engine for you. Whether this is the cure to your problem I cannot guarantee.

    As said my RE WILL NOT START without choke. End of. Soon as I swapped out the carb it has been fine. If it starts with choke then sweet.

    Anyway for peace of mind I am happy for you to ship the engine to me and I will rebuild it. Then you knows you have a sweet engine.

  • Thanks for the offer, I very well may come ask you if you're still willing in a couple months. It's definitely something I want to get done.
    Right now though, I don't have the cash. I'll likely come and ask you for details once I get paid 🙂

    I also need to figure out this starting problem which I'm going to quiz the forum on in a separate thread, seems seperate enough from the engine rebuild to warrant a new one.

    Thanks for your advice.

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