PICTURE_MAN36 Posted August 31, 2011 Posted August 31, 2011 Hello. Appreciate its an old bike, but I'd be appreciative if anyone can help with my problem. I am in the process of restoring an '83 / Y plate Yamaha DT125MX. I have taken the clutch cover off to flat it and paint it, and have disconnected the oil pump. Whilst it was off, I checked the pump and found the reason why the previous owner had run it on premix. The oil pump was seized. I bought another oil pump from a DT175MX on EBAY. The seller said that it was also for the DT125MX. Having painted the panel, I am now in the process of putting the pump back in the casing, and putting the casing back on. I have checked the new pump, and it is not seized, and the gear rotates with my finger. I have put my shaft from the 125, into the pump, and it is as if the worm gear on my shaft does not match with the gear wheel in the pump. If I put the collar in the pump the shaft locks up completely, and the pump will not go anywhere near the casing. I've taken chunks out of my fingers, and I am in danger of knackering the casing I've just painted, so I have come away for the evening. Does anyone know if the worm gear is different on the 125 & 175 AND if I do have to match up a '175' shaft with my '175' pump, will this work with my 125 (Which incidently now has a 175 barrel and head on it any way. Any help you can offer would be appreciated. Thank you
Moderator Airhead Posted August 31, 2011 Moderator Posted August 31, 2011 Hello. Appreciate its an old bike, but I'd be appreciative if anyone can help with my problem. I am in the process of restoring an '83 / Y plate Yamaha DT125MX. I have taken the clutch cover off to flat it and paint it, and have disconnected the oil pump. Whilst it was off, I checked the pump and found the reason why the previous owner had run it on premix. The oil pump was seized. I bought another oil pump from a DT175MX on EBAY. The seller said that it was also for the DT125MX. Having painted the panel, I am now in the process of putting the pump back in the casing, and putting the casing back on. I have checked the new pump, and it is not seized, and the gear rotates with my finger. I have put my shaft from the 125, into the pump, and it is as if the worm gear on my shaft does not match with the gear wheel in the pump. If I put the collar in the pump the shaft locks up completely, and the pump will not go anywhere near the casing. I've taken chunks out of my fingers, and I am in danger of knackering the casing I've just painted, so I have come away for the evening. Does anyone know if the worm gear is different on the 125 & 175 AND if I do have to match up a '175' shaft with my '175' pump, will this work with my 125 (Which incidently now has a 175 barrel and head on it any way. Any help you can offer would be appreciated. Thank you you need to fit the shaft from the 175 pump too but i assume you didnt get it in the sale
PICTURE_MAN36 Posted August 31, 2011 Author Posted August 31, 2011 Thanks. That's what I thought but the seller sold this item seperately so I guess I am up the creek without a paddle. Just had a look on EBAY for a pump, and there is nothing to be seen. I guess its a call to the local Yamaha dealer tomorrow, and a trawl through new old stock lists. I've contacted him but had no response yet. I thought it was me. I guess that the worm gear on the 125 & 175 different. Thank you
PICTURE_MAN36 Posted August 31, 2011 Author Posted August 31, 2011 Just looked on EBAY roughly around the same time and the shaft, and drive gear were sold for a few quid seperately, and from the photo the worm gear appears to be different to mine. It looks like the gear on the shaft which went with this pump is a lot coarser thread, and mine is finer. Guess that this means that the 175 pump is geared different to the 125. I'm a bit stuffed now. The pump that came with my bike had seized, and the driver gear in my pump has lost some teeth. The replacement pump works fine, but won't match with the fine thread on the worm gear on the 125 shaft... Happy days.... Many thanks for your response.
PICTURE_MAN36 Posted September 1, 2011 Author Posted September 1, 2011 Finally a conclusive answer to the question. Spoke with the local dealer, and the DT125MX & DT175MX have different pumps and drive shafts. Suppose its logical; bigger barrel = more 2 stroke oil! If anyone is looking to put the 175 barrel on a 125 bottom end, you will need the 175 pump, and shaft! Now the hard part; unless I can source a 2nd hand shaft to go with the pump, its a trip to the local dealer, and £26 from the wallet!
kiln Posted September 3, 2011 Posted September 3, 2011 You can always get the proper part from http://www.nwvcp.com/pages/oemparts/viewbybrand/parts.aspx
PICTURE_MAN36 Posted September 5, 2011 Author Posted September 5, 2011 Thanks. Spoke with my local Yamaha dealer in the UK, and the part I need is still available from Yamaha central stores in Japan. I was trying not to pay the dealer price, but it looks like I have no choice. I've spoken with a company locally who do new old stock, and they're comming back to me. I should have realised that the 175 barrel will need more oil; I'm trying to mate a 175 top end with a 125 bottom end to give me a few more horse power. I've had the carb rejetted, and just want to get the engone back together and crated up. Thanks for your response. Cheers
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