A bit of a rattle in a DT250a, could ya'll have a listen?

OffBeat · 03-06-2013, 02:23 PM

A friend dropped a Yamaha DT250a off to me. It runs really, really well other than a bit of a rattle. This video/audio makes it sound a little worse than it really is. My son was putting some miles on it in the dirt at our house (we have a few acres) and have trailer-ed it to some woods. Not sure if the oil injector is working as it should so we put pre mixed oil / gas in it. Couldn't ask for a better running bike. Just has this rattle. Any ideas??? Thanks!

stainlesscycle · 03-06-2013, 04:02 PM

sounds like a small or big end bearing to me. pull the top off of it and have a look see.

OffBeat · 03-06-2013, 05:03 PM

Quote:

Originally Posted by stainlesscycle

sounds like a small or big end bearing to me. pull the top off of it and have a look see.

Thanks for the suggestion. Getting some ideas ready and when the snow melts some and the temps get above freezing I want to investigate. I was checking on a battery tender on my KLR today and couldn't help but fire up the little bugger and make some noise. Crikey, the thing has been setting since last fall and it only took two kicks and it was off and running! Thanks again, Bill

YZEtc · 03-07-2013, 02:50 AM

Sounds like large-ish piston/cylinder clearance (wear).

lrutt · 03-07-2013, 03:59 AM

yup, piston slap, no doubt. They are worse when cold. Easy to check your injector, pull the line from the side of the cylinder when it's running and see if the oil is pumping out. A brief disconnect won't hurt. Get a manual and set it proper would not hurt although unless someone has been mucking about they won't go out of adjustment.

If you are tasked with making the bike proper, use an OEM Yamaha piston and rings. A forged Wiseco will require even larger piston / bore clearances and make the rattle worse than it needs to be.

My RT1 I'm redoing was that bad or worse so I picked up a NOS piston and rings for $50, plus a gasket set (complete) for $20, and bored the cylinder for $50. Motor is good to go for a long time now.

that is a mighty clean 74 you got there.

OffBeat · 03-07-2013, 06:40 PM

Thanks for the replies! Looks like I will have plenty of fun things to look for when I get the time.

I will give the injector a try with the hose off and see what I can see, thank you. I have a Clinton manual for the bike. I will take a look and see if any of what they have to say makes any sense.

My friend gave me the bike as I had one back in the 70's and he had a 360 that we road all over the place. We will locate the 360 for him and see if we can get out in the dirt again.

Here are a couple more pics of the bike I took last summer before putting it away for the winter. Thanks again, Bill

anonny · 03-07-2013, 08:00 PM

Nice bike, I'm gonna go with piston slap too. Wossner might make a piston for you too.

http://www.wossnerpistons.com/

buls4evr · 03-12-2013, 09:51 AM

It is not the oil injection so leave it alone and run straight gasoline in the tank. It will not help shot rings, piston and small end bearings to throw extra pre-mix on them. Fix the top end problems. The DT series were quite susceptable to worn small end cages/needles. Before buying a piston chk the fit. May only need rings and a fresh needle cage.

OffBeat · 03-12-2013, 11:40 AM

Will do! The reason I add oil to gas is that oil level hasn't gone down any after several tanks of gas, and I do mean "not a drop" down.
Had to mount the plow back on the truck to deal with snow and driveway issues. Will be looking forward to getting the bike into the shop and checking all above when the weather breaks. Tired of snow and cold!!

Quote:

Originally Posted by buls4evr

It is not the oil injection so leave it alone and run straight gasoline in the tank. It will not help shot rings, piston and small end bearings to throw extra pre-mix on them. Fix the top end problems. The DT series were quite susceptable to worn small end cages/needles. Before buying a piston chk the fit. May only need rings and a fresh needle cage.

RideFreak · 03-17-2013, 11:13 PM

Piston slap, also sounds like the rubber fin dampeners are missing, they ring allot when those get removed. Might have a forged wiesco in it too, noisey bastards.

joexr · 03-20-2013, 01:54 PM

Quote:

Originally Posted by RideFreak

Piston slap, also sounds like the rubber fin dampeners are missing, they ring allot when those get removed. Might have a forged wiesco in it too, noisey bastards.

Ditto. If it still runs good its nothing to worry about. Unless of course you can start it with your arm.

OffBeat · 03-20-2013, 03:57 PM

Quote:

Originally Posted by RideFreak

Piston slap, also sounds like the rubber fin dampeners are missing, they ring allot when those get removed. Might have a forged wiesco in it too, noisey bastards.

Well, you got me to thinking. Put my snowshoes on and made my way out to the pole barn. Took a peek, 7 dampeners on each side of the jug. Not very springy, I'm sure, but they were there.

Figured, what the hell. Gave it 3 kicks and it started up. I don't notice the rattle under load. Though, to be honest, I don't have much hearing left in these old ears. Only when you you let off on the throttle. Got it all warmed up nice, did a few circles raising some dust in the barn and then backed it back into it's sleeping spot till I have time/warmth to dig a little deeper.

Thanks again for all the great suggestions.
Bill

03-06-2013, 02:23 PM	#1
OffBeat ^OP Fart Knocker Joined: Aug 2008 Location: Traffic City, MI Oddometer: 41	A bit of a rattle in a DT250a, could ya'll have a listen? A friend dropped a Yamaha DT250a off to me. It runs really, really well other than a bit of a rattle. This video/audio makes it sound a little worse than it really is. My son was putting some miles on it in the dirt at our house (we have a few acres) and have trailer-ed it to some woods. Not sure if the oil injector is working as it should so we put pre mixed oil / gas in it. Couldn't ask for a better running bike. Just has this rattle. Any ideas??? Thanks!

03-06-2013, 04:02 PM	#2
stainlesscycle Beastly Adventurer Joined: Jun 2008 Location: morgantown, wv Oddometer: 1,639	sounds like a small or big end bearing to me. pull the top off of it and have a look see. __________________ current bikes 07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more

03-07-2013, 03:59 AM	#5
lrutt SILENCE.....i kill you Joined: Jul 2005 Oddometer: 796	yup, piston slap, no doubt. They are worse when cold. Easy to check your injector, pull the line from the side of the cylinder when it's running and see if the oil is pumping out. A brief disconnect won't hurt. Get a manual and set it proper would not hurt although unless someone has been mucking about they won't go out of adjustment. If you are tasked with making the bike proper, use an OEM Yamaha piston and rings. A forged Wiseco will require even larger piston / bore clearances and make the rattle worse than it needs to be. My RT1 I'm redoing was that bad or worse so I picked up a NOS piston and rings for $50, plus a gasket set (complete) for $20, and bored the cylinder for $50. Motor is good to go for a long time now. that is a mighty clean 74 you got there. __________________ 2004 Harley Sporster 1200C, 2001 Ducati M900, 2001 Honda XR650L, 1994 Harley Heritage, 1978 Honda CB750K with sidecar, 1977 Moto Guzzi 850 LeMans, 1976 Honda CB750K, 1965 Honda 305 Dream, 1973 Norton 850 Commando, 1971 Triumph Trophy 650, 1970 Honda Trail 90, 1970 Triumph Tiger 650, 1973 Honda Z50, 1984 Yamaha Virago 1000, 1981 Honda Passport 70, 1970 Suzuki T250, 1971 Yamaha RT1 360

03-07-2013, 06:40 PM	#6
OffBeat ^OP Fart Knocker Joined: Aug 2008 Location: Traffic City, MI Oddometer: 41	Thanks for the replies! Looks like I will have plenty of fun things to look for when I get the time. I will give the injector a try with the hose off and see what I can see, thank you. I have a Clinton manual for the bike. I will take a look and see if any of what they have to say makes any sense. My friend gave me the bike as I had one back in the 70's and he had a 360 that we road all over the place. We will locate the 360 for him and see if we can get out in the dirt again. Here are a couple more pics of the bike I took last summer before putting it away for the winter. Thanks again, Bill __________________ 2000 KLR650 1974 DT250a 1965 VW Sedan (for when it rains!)

03-07-2013, 08:00 PM	#7
anonny What could go wrong? Joined: Mar 2007 Location: Beautiful Revelstoke BC Oddometer: 4,960	Nice bike, I'm gonna go with piston slap too. Wossner might make a piston for you too. http://www.wossnerpistons.com/ __________________ Kawasaki H1 build thread 71- 450 Honda CL re & re Just another pathetic sheep following the herd

03-07-2013, 02:50 AM	#4
YZEtc Feel lucky? Joined: Nov 2010 Location: Connecticut Oddometer: 77	Sounds like large-ish piston/cylinder clearance (wear).

03-12-2013, 09:51 AM	#8
buls4evr No Marks.... Joined: Sep 2009 Location: Michissippi & Nuevo Mexico Oddometer: 1,610	It is not the oil injection so leave it alone and run straight gasoline in the tank. It will not help shot rings, piston and small end bearings to throw extra pre-mix on them. Fix the top end problems. The DT series were quite susceptable to worn small end cages/needles. Before buying a piston chk the fit. May only need rings and a fresh needle cage.

03-17-2013, 11:13 PM	#10
RideFreak Torque Junkie Joined: Apr 2009 Location: County Lockup Oddometer: 3,552	Piston slap, also sounds like the rubber fin dampeners are missing, they ring allot when those get removed. Might have a forged wiesco in it too, noisey bastards. __________________ *Chris* VIDEOS

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