Vintage Dirt Bike Q & A

Does anyone know how can you tell if the oil injector system is working without starting the bike. I just bought several TM's and I have got one 400 and one 125 on their way to being restored. I can not tell if the injector system works for sure. I don't want to mess it up trying to check and see. I heard that there is a plate on the crankshaft that blocks lubrication in the gas from getting to the left crank bearing and extra oil from getting in the gas. I mean I do not know the history of these bikes, someone could have already done the modifications necesary to run premix. I just have never been a fan of injector systems. When I have premix I am sure everything will be fine but you never know when mechanical failure of an injector system might pop up. The 125 I have has the tank removed and the hole fore the line plugged up. It has good compression and the crank beaings feel good, but someone may have unhooked it and messed it up trying to run premix or something. I am just trying to avoid an expensive rebuild of the bottom end but looks like I may have to to be sure. I don't mean to sound stupid about all of this but I figured someone has crossed this bridge before and any advice on gas & oil ratio's, injector system, etc would be greatly appreciated. This is all a new animal to me. I have had other 2 strokes with injector systems and it was as simple as unhooking it and running premix. This is not the case with the TM's and I need advice......Thanks alot in advance

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79 RM50
80 RM60
79 RM80
74 TM125(3)
72 TM250
73 TM250(3)
74 TM250
75 TM250
73 TM400
74 TM400(2)
75 TM400
76 RM370
78 DR370
781/2 RM250
78 RM400(2)
79 RM400
80 RM400
73 Hus 400CR
77 Hus 390CR
73 CZ 400
78 Z50
81 CR450
74 KV75
85 KX250
79 YZ400
05 PW50

The modification is to drill holes so the mix will reach the bearings. Kind of off topic but when you get sealed bearings from a bearing supplier and explain they are for a 2 stroke, the counter person will tell you to just poke out the seal.

*BUT* I run 50:1 in my oil injector bikes, Honda and Suzuki, anyway. I am probably a bad example. I suppose I could just remove the oil feed pipe at the oil tank and run the bike for a few minutes to see if level in the tube goes down.

Rick

Thanks for yur help. I believe i found the trick. What has to be done is that there is a smal round "plate" (for lack of a better word) that fits between th bearing and they crank. The plate has to be trimmed down so the mix can reach the bearing. You have to leave a small pipece of it so that evertyhing is still spaced correctly. The trouble I have gotten into is that I have bought severl bikes that i do not know the history of. This mod may have been done or it may have not been done. I bought a swet TM125 and for the life of me I can not figure out why it was not running. It looks like a new bike, but the oil injection sysytem is unhooked. I have to figure out is someone ran the bike with premix and then messed up that left crank bearing or they might have done the modification correctly. I guess I will just hook the injection system back up and see if it runs ot ok. I don't want to damge anything like my cases. I should be able to tell if everything is good to go when I hook up the injection system. I mean the crank turns nice and there are no abnormal noises so either the mod has been done or someone just robbed the injection system and never ran the bike. Would hav been nice if Suzuki had made the bike where all you had to do was unhook the injection system and run premix.

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79 RM50
80 RM60
79 RM80
74 TM125(3)
72 TM250
73 TM250(3)
74 TM250
75 TM250
73 TM400
74 TM400(2)
75 TM400
76 RM370
78 DR370
781/2 RM250
78 RM400(2)
79 RM400
80 RM400
73 Hus 400CR
77 Hus 390CR
73 CZ 400
78 Z50
81 CR450
74 KV75
85 KX250
79 YZ400
05 PW50