Moderator Cynic Posted March 16, 2009 Moderator Share Posted March 16, 2009 Hi all, my DT engine is a bit sick. She has finally called time and demanded some serious attention. She had an overhaul of the running gear about 10 years ago but the motor was ok and as one of the ain't broke brigade, i left well alone.... Point is i've established that the crank seals have gone so am pulling the motor down, i've started from the off taking pictures so i am going to try and do it as a long thread and try and scare away some of the fantasies over whats inside these motors and that its relatively simple to tackle the big jobs. Anyho this is the most recent piccy of the old girl just b4 i set to getting the motor out.. The first thing to do is tidy the garage, yes seriously, the second is go to the pound shop. I got 20 odd assorted plastic containers with lids, 10 round foil tins and a stainless turkey baster (perfect for degreasing) with a bottle of lamp oil ( like parafin but a third of the price) for under a tenner. Then sort out your bench, and your storage for the stripped parts Now, still not very exciting and rather tedious, clean all the grease oil and rubbish off the outside. Otherwise you will get it over you tools, yourself, the bench and most importantly the nice clean internals. This is where i'm upto at the mo. I will be pulling the barrel and the clutch etc this week and looking into getting the bits orderd to fix it, the awqward one being a barrel, anyway i'll finish on a shot of the motor as it is at the minute and i'll update later in the week. One nice clean motor..... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 17, 2009 Moderator Share Posted March 17, 2009 Looks like an interesting topic here Jason, should make a good horror story eh, Are you planning a full engine split with the cases split, possible bearing replacement? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 18, 2009 Author Moderator Share Posted March 18, 2009 I'm inclined to do them, they seem OK but i have flooded the crankcases with water myself twice, so i think i would be a bit of a prat if i didn't take the oppotunity. The crank appears to be absoloutly fine i will check when its out. I have been trying ot get a photo that shows it but one of the crank seals ( LHS) was put in on the piss by whoever had it apart last. Surprised its lasted this long. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 19, 2009 Author Moderator Share Posted March 19, 2009 Ok bit further on, the top end is fubar unfortunately or unsurprisingly. This is the nasty bit on the barrel, some teenage bodging i'm not very proud of but is not all that uncommon for any old trailee, steel studs in an ally barrel they sieze and they snap. Leading to this ahem. As its on 1.25 as is and a knackerd 1.25 at that i really don't think it is worth the expence of sorting it properly. The head gasket has also failed as you can see from the pictures it was blowing at the exhaust and leaking at the head so its not surprising the piston has melted at its crown, it is also out of spec in all ways with scoring on the front and a scar from a heat sieze couple of years back. on the plus side the clutch has stripped down fine, all the plain plates are flat and the friction plates are all well in spec, the drum its self is also in great condition, in fact the only bit of wear i can see is the polishing on the clutch output shaft but thats to be expected as its a bearing surface for the basket. Thats about it for now well till i get the cases split. If you want to know or see about something specific or you have any pearls of wisdom/experience pile in. I'm not doing this as a manual, just showing that its no black art. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 27, 2009 Author Moderator Share Posted March 27, 2009 Well the saga continues. The cases have now been split but it was begining to look like i was going to have some troubles. The selector mech all stripped down loverly apart from the gearchange cross shaft, that was very happy where it was thank you, once it was out it proved to be dried up grease causing it to stick. After cleaning the muck off it is fine with good splines and straight. First, and very critical issue is someone had this motor to bits on the cheap and has caused me a load of grief that would have been easily prevented. Everything has been done up FT as in Fcuking tight, as a result i have been using the battery spanner for 5 out of the 12 case screws as well as the crank and output bearing retaining plate screws, Heat and or releasing agent has done for the rest, stud extractors generally cause more hassle than they are worth unless conditions are perfect. Soft ally cases stressed by the extractor forcing its way into the offending item, i'd sooner drill em with steadily bigger bits, go steady and slowly only clamp the drill in the chuck just enough ( then if it bites it won't snap) and use A LOT of lube and they nearly always come out clean and leave the thread relatively (depending on how straight you were) untouched. So screws removed, crankcase splitter fitted made for me by OGOAB and very thankful i am too as without him mentioning the need for the splitter i would have done no more than followed the manual that makes NO MENTION of it. I did find that the cases did bind at the back where the rubber engine mount is, why have one rubberised and not the rest?? Not really a lot on the inside, could say its almost dissapointing. The crank according to the manual should tap out of the left hand case. All i can say is I hope whoever wrote that never taps me on the head or i'll be out for a month. The good news is the gearbox is in great nick, no obvious wear, forks look good and the gearbox bearings are all good, great. This initially is where i stopped to get the parts at the beginning of the week and after pricing it all up with pattern stuff from Wemoto found that i could have it all genuine for about another 25 quid, no brainer really. The no brainer in question is TYtrials and more importantly a bloke called John, sorted all the bits i need to rebuild the bottom end as well as a complete engine set of allen screws, Don't that look prretty, get what you pay for. Something else i was informed of. Apparently bearings have speed load and temperature ratings. A bearing of the right size does not a main bearing make. A lot of pattern main bearings are just bearings the right size and not necessarily the right rating and can fail very early. John also said that if you are stripping an engine do it right, strip it RIGHT down as you will be amazed at where crud and siht gets to as well as pockets of swaf from warn bearings just waiting to knacker the new stuff. Also whenever you split the cases on a DT change the output shaft bearing cos it gets hammerd by muck and rubbish and is always always worn. And the bit thats forgotten most often? The o ring on the primary side of the crank, it is vital to the seal of the crank and apparently its very often left when people do the cranks, they just change the seals. He also went into changing the bearings themselves and how, i wont go into that now i'll save it till i've done it and can comment but it envolves a heat gun. Right now i'm ready to start changing bearings with 2 nice clean crankcase stripped down to just their bearings. I deliberately havent prettied or polished them just a REAL good clean. I dont want to scrub away the fact that its getting on for 30 years old. I'm afraid i quite like the 'comfy slipper' look. Any how a few piccies to finish for now. A nice clean case. The engine's current home. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 29, 2009 Author Moderator Share Posted March 29, 2009 Ok as i'm writing this the missus is muttering nasty things under her breath, she went out with the girls this morning and i promptly lobbed the cases in the oven at max. The bearings have been in the freezer since i got em. Cases out of the oven, bearings out the freezer and they did no more than drop straight in, literally without so much as a tap, just got to leave them now for an hour or so to cool so the bearings can 'grow' into place and lock in nice and solid, don't forget that the lettering has to be facing the side that would be struck if you needed to. The only annoying thing is i have the wrong output shaft bearing, its for a TY surprisingly enough. Still i'll get that sorted monday so the motor will be going back together this week. Thats if i can apease the missus, she got back as i was taking the cases out the oven, oooops. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 17, 2009 Author Moderator Share Posted April 17, 2009 Back again, quick update. Had one of those silly thoughts, y'know the one. 'Well if i'm sorting the motor out nice i really should......' . Its an open ended sentance as it doesent seem to stop. I now have a completely stripped frame in the garage a sw arm with a mutilated (due to being solid) sw arm spindle and the rest of the bike spread around the garage. I started to build the bottom end of the engine back up tonight, same again, crank in the freezer and on orders from the kitchen a heat gun ( i know when i'm beat) and the crank slid in loverly. I have the new seals and bearings in and they feel smoooooooooth. I think those mains have been rough for a long while. I very nearly forgot that bloody o ring on the crank too. There is a company local to me who can sort the barrel for me so that will be away to be fixed up. I'm going to have 8mm studs put in. A common mod on the IT by all accounts, (anybody knows better shout) cos they snap the 6's. I have a few pics of the carnage in the garage so far and i'll lob them up over the weekend. Link to comment Share on other sites More sharing options...
1978Dt175 Posted May 20, 2009 Share Posted May 20, 2009 I just picked up a 78 dt175 for 60 dollars American, and I am in the process of rebuilding it. I tore into the engine today and found the piston is .02 over and the engine had been rebuilt recently (it had great compression). I know very little about these engines and was wondering if you could post a link to some reference material on the internet. Any help would be appreciated. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted October 17, 2009 Author Moderator Share Posted October 17, 2009 Well, frame stripped and here it is painted, now the suzuki has gone i have permission to carry on. Apparently a v8 rangie and 3 bikes was a bit much. lovely. The engine is now sorted apart from the top end i have managed to get hold of no less than 2 barrels that are on their original bores and good coils/ carb and pretty much a whole motor for 70quid result. I was going to use pattern pistons but i have noticed that there is quite a difference between the OEM pistons and the pattern stuff. it really is a 'get what you pay for situation'. Anyway the motor is in and i've started putting the bike back together properly now. Its not, and was never going to be any more than a mechanical rebuild so cleaning up is the main aim. Rather than pretty. there are plenty of DT's out there in beautifully preserved condition that never get used. mine is in the used and abused camp. The TDR gets a lot of tlc, but that is all original. Here she is at the last pic, i'm putting the forks together now. using the bits from two sets to get a good pair. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted October 17, 2009 Moderator Share Posted October 17, 2009 I am glad you brought this thread back to life. A great thread for all DT175 owners, in my opinion. Cable and electrics routing pics would be great. Link to comment Share on other sites More sharing options...
philhill Posted October 18, 2009 Share Posted October 18, 2009 Hi Cynic, Great thread, having just done this myself twice I wish you had posted a couple of weeks previous! Anyway just to let you know, as you gave me some helpful advice, my DT175 was finished yesterday and has run perfect from Mansfield to the Stafford show and back without any problems. Spark plug chocolate brown again! There was a hell of a lot of metal bits in the crank case chamber though, I don't think much went out the exhaust! Thanks Phil Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 18, 2009 Moderator Share Posted October 18, 2009 Yep, light at the end of the tunnel now, frame looks good, a rub down prime and PJ1 frame paint or what? makes a refreshing change to the usual route of powder coating anyway Youre doing the forks now, the sliders do look good painted too, I did mine, covers up the corrosion that they almost inevitably have, quick and cheap too. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted October 18, 2009 Author Moderator Share Posted October 18, 2009 Yep, light at the end of the tunnel now, frame looks good, a rub down prime and PJ1 frame paint or what? makes a refreshing change to the usual route of powder coating anyway Youre doing the forks now, the sliders do look good painted too, I did mine, covers up the corrosion that they almost inevitably have, quick and cheap too. Yep good old fasion'd hamerite, then when (not if) it gets scratched etc its 2 minutes with a touch up rather than ruining the powder coat. And its cheap. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted October 20, 2009 Author Moderator Share Posted October 20, 2009 Hmm how this for reason to check everything properly, The jug shows how much oil was in the fork, the metal tray is showing the crap stuck in the fork bottom that i rinsed out with parafin. They weren't my forks i'd like to point out they are a set from a scrapper i picked up. It must have been like riding a bouncy castle. Something else, although i forgot to take photo's (doh) the sw arm bushes turned up and caused a little confusion as i could not tighten the arm up so that there was no play. And thats without any shims either. After scratching my head and a couple of brew's it became obvious. The sleeve was too long by about 1mm. I trimmed it down (with a grinder, bloody hard stuff that steel) and it tightend up loverly. Link to comment Share on other sites More sharing options...
tommy Posted May 2, 2012 Share Posted May 2, 2012 Hey there, Great looking project! I noticed you asking:" why have one rubberised and not the rest??" on the engine mounts. After a few sleepless nights over a rebuilt engine that had had serious ignition problems after it was finished, I can now tell you that you will at least need one of the engine mounts to make GOOD electrical contact with the frame. So when you remount the engine, either sand the holes where the bolts go in the frame to the bare metal and make sure your bolts are clean or if you don't want to ruin the corrosion-protection from the paint job on the frame you may want to install a ground wire from the engine to the frame. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 2, 2012 Author Moderator Share Posted May 2, 2012 Ha Ha Ha i've been riding it 2 years since that post. Link to comment Share on other sites More sharing options...
flyday58 Posted May 2, 2012 Share Posted May 2, 2012 How about some finished piccy's? Reminds me, I need to disassemble mine to take pics of the reassembly... Link to comment Share on other sites More sharing options...
tommy Posted May 2, 2012 Share Posted May 2, 2012 OK, so now you know, some people (me, for instance) are foolish enough not to consider their engine needs to be grounded. Came across this topic looking for info on an engine rebuild for my bike. Should have checked the date before replying to your post. Anyway, are you still riding that DT? And how is it now, 2 years after the rebuild? See, funny thing is, everywhere you can find people's pictures of disassemblies, but people are usually too busy rebuilding and riding theirs to take pictures once their project is comming together. (I'd probably be just like that, BTW) Also If you have info/pictures on how to restore/rebuild a front fork; that's the next thing I need to tackle on mine. Link to comment Share on other sites More sharing options...
samnrflt Posted February 20, 2015 Share Posted February 20, 2015 I have a 1971 CT175 that has a seized transmission. I don't think i have the right tools to crack the case any further. I got the clutch case off and now I'm stuck with that drum. It spins when I try to unscrew it. I've never done something like this before. How do I pull all of those parts out so I can inspect inside of the case? I'll post pictures later if needed. thanks! Link to comment Share on other sites More sharing options...
blackhat250 Posted February 20, 2015 Share Posted February 20, 2015 Hi sam , you get a clutch tool , or an air gun , , you-tube has yz250 tear downs , similar to the DT, Link to comment Share on other sites More sharing options...
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