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DTR 125, problems


Taffman92
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hi, ive had the DTR for about 3 weeks now and there's a couple of little things ive noticed and am not to sure about as Im a carpenter not a mechanic lol, firstly the exhaust manifold, I was riding home one day and noticed a rattling noise coming from the exhaust, when I got home I took a look and noticed where it bolts on to the engine it was loose and moving slightly when the engine is running causing the rattling noise so I tightened it up, however!! when I took it out to see if it fixed the noise ( it did! ) the bike started losing power and just started dying, took it home loosened it back off and it was fine again, but it rattles all the time when im riding, any idea's on this ???
.

second thing is the bike once its warmed up will start to revv up on its own up to 3500 revvs and if I lift the choke up it starts to idle lovely, but as soon as the choke is down up the revvs go, gets a little annoying when I'm at a junction and it sounds like I'm holding the throtle open a bit, I havent got a clue with this ??

third problem I've found is that the speedo is not working ( not sure if the PO disconnected it to save milage ), how do I check to see why its not working??

P.S , not sure if this helps but the guy who sold it to me told me its been derestricted,

now like I said up top , I'm no mechanic but I'm not a complete idiot with tools, if anybody can help with any of these problems It would be most appreciated, but try and explain in layman's terms lol

Thanks, Taffman92

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Hi there

To adjust idle rpm there should be a thumb screw turn it out anticlockwise slow until desired rpm reached!

Speedo isn't working could be 3 things-cable snapped (most likely) speedo is broken or broken speedo drive (on front spindle) you need to get the front wheel jacked up disconnect cable by the clock end spin front wheel by hand and see if the cable inside is turning!

As for the exhaust sounds a little strange, your saying the when its loose the bike runs better???

Either the exhaust system is blocked/coked up or there is a restriction in the chamber still.

Hope this helps

Ken

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Woah. This needs sorting quick.

The engine to exhaust seal should be airtight. If not the bike will go massively lean. Hense the 3500rpm.

Using the choke is correcting the mixture after a fashion. Seal the pipe up then check your air filter. That may be partially blocked but you will lose a little go as running lean gives more power. Problem being the cyl runs too hot and pistons melt, (yes litterally). So a slight trade off is needed.

If you keep running with the loose exhaust you WILL BLOW THE MOTOR. Costing at least a rebore.

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cheers for the replies, hopefully I'll have time tomorrow or Sunday to look into trying to fix these problems, to answer the questions , it is a full DEP system on it and the mileage is just over 15000, but like I said the speedo is not connected so ??? , the PO did say the engine had been rebuilt and it had a new crankshaft and piston fitted , the bike had been taken right back to the frame and every nut, bolt and washer renewed ,

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well I managed to tighten up the manifold as much as I can one one bolt as the other one is jammed solid and will not budge , no rattling and it didn't die or start to lose power on me like last time, but it's still revving high, when I start it up first it will idle lovely but once I've gone down the road and stop at a junction it starts to idle at 3000 to 35000 revvs ?? I don't think turning the idle screw will fix it as it idles ok on first start up,,

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L/H crank seal shot gives this type of reving issues. I would doubt it had a new crankshaft as this would be mighty expensive.

Crank seal symptoms - Revs OK when cold but when it is warm it starts to rev high and doesn't come back to tickover quickly. Slowly lowers the revs but will cut out. If you rev it. It sticks at high revs, which can be embarrassing at lights.

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today after work on the way home, its starting to die on me again, when I let the revvs go low it just dies, completely the opposite to the over revving and I haven't touched it since tightening the exhaust, it rode fine on the way in to work and started dying after about 5 miles into my ride home, thought I'd try the idle screw but it still does it ,,

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Sounds to me like the throttle cable free play needs some adjustment.

An easier way to test the speedo cable by the way, disconnect it at both ends, and then twist one end with your fingers, you should see the other end move. If not your speedo cable is broken. If it's moving when you twist it with your fingers, then connect it to your hub, turn the wheel by either pushing the bike or have it up on a stand, and just watch to see if the other end of the cable moves. If it doesn't, try pushing the inner cable down into the outer cable a bit, and repeat the process to check if it's moving with the wheel. If not then your hub is the culprit. If all is fine here, then reconnect it to the speedo, making sure that it's properly seated and threaded. If you're still having no joy then the speedo is your culprit.

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it does it even when I hold the throttle open at 2500 revvs , just starts to lose life, might try checking the fuel line and carb for blockages and clean the airfilter tomorrow,

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it does it even when I hold the throttle open at 2500 revvs , just starts to lose life, might try checking the fuel line and carb for blockages and clean the airfilter tomorrow,

It sounds to me like it's leaning off after a certain point... almost as though one of your jets is blocked.

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After Taking off the carb and cleaning out the jets ( one was well clogged up ) the bike kicked over and seems to be ok now :D haven't taken it for a run because a couple of the screws were well tight and it was a struggle to get them out, the screw for the drain in the bowl is impossible to get out so it will have to stay there lol, so I didn't finish till late and I had to do it in the rain and I got soaked, but I think I must have broke something because the choke won't stay up when I turn it on :( . I disconnected the speedo cable from the drive on the wheel and put a drill on the end of the cable and the needle moves :) but the end of the cable where it goes in the drive looks a bit to short so I'm gonna get a new cable first then if it still doesn't work a new drive, so thank you all who gave me advice on this. just a shame I think I broke the choke but I should be ok with holding it up to start the bike lol

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