I’m currently running a DT100 engine with an RT100 jug and reed, DT100 head, and I need support with point timing. I’ve sealed everything correctly, fuel is reaching the engine, and compression is good—but the bike still refuses to start. I’m confident the issue is timing-related..Where I Need HelpBecause I’m running an RT100 jug (different port layout and airflow characteristics), I’m unsure if I should stay with DT100’s stock timing or if anyone has experience with:

• Slightly retarding or advancing timing to match an RT jug on a DT bottom end
• Confirming the correct point gap (I don't have a Guage)

Any guidance, reference images, or step-by-step confirmation would be highly appreciated. This is my first build, and I’d like to get this right.

if your plug is not "wet" then take carb off and run guitar string thru the pilot jet. tighten reed intake manifold bolts (these loosen often) 1982 dt100 had points? i had thought cdi in 82..? hmmm. one time my 74 dt100 original stock plug cap tested bad and i had to replace. there is a diode in there or similar component. the disconnect your stator magneto connection. get a multi tester, one probe on the black wire stator side and the other probe to good ground frame bolt no paint. look for when the meter changes from points opening and closing. i forgot the exact specs like it will jump from 6.0 down to .3 or .4. eyeball it to see which one is which. get your handy chop stick put it in the cylinder or if u can tell when piston tdc . there might be a curved half arrow timing mark on your magnet. that mark should be at 12 noon. btdc is about 1 or 2 oclock, your multimeter should be changing crunch numbers at around 1 or 2 oclock btdc and just before that curved half arrow mark hits 12 oclock. before any of this set your gap so you are already close to timing. with timing curved half arrow at 12oclock piece of printing paper slipped in between your points should be slightly feel drag when feeling the play in between the point contacts. like snug just before the paper can just fall out. get canned air or air hose to see if you can air the paper out of the points . indirect air should not be able to move the paper, its that close . dont use manilla paper nor business card those to thick. paper can be as tight felt as holding a potato chip. then time it after that. turn lights off when looking for spark and also hold the plug with hand pressure to non painted fin on your jug. one time mine was sparking and i was missing it because of the little things. then magneto connection black wire should be going into the black/white wire. if no spark unplug kill and confirm good ground at under gas tank coil . coil should be plugged into black or blk/white. also if you dont have battery in it be sure to tape up and unplugged wires to make sure nothing from harness is touching ground and grounding things out. if your plug is not "wet" then take carb off and run guitar string thru the pilot jet. tighten reed intake manifold bolts (these loosen often) 1982 dt100 had points? i had thought cdi in 82..? hmmm. one time my 74 dt100 original stock plug cap tested bad and i had to replace. there is a diode in there or similar component. the disconnect your stator magneto connection. get a multi tester, one probe on the black wire stator side and the other probe to good ground frame bolt no paint. look for when the meter changes from points opening and closing. i forgot the exact specs like it will jump from 6.0 down to .3 or .4. eyeball it to see which one is which. get your handy chop stick put it in the cylinder or if u can tell when piston tdc . there might be a curved half arrow timing mark on your magnet. that mark should be at 12 noon. btdc is about 1 or 2 oclock, your multimeter should be changing crunch numbers at around 1 or 2 oclock btdc and just before that curved half arrow mark hits 12 oclock. before any of this set your gap so you are already close to timing. with timing curved half arrow at 12oclock piece of printing paper slipped in between your points should be slightly feel drag when feeling the play in between the point contacts. like snug just before the paper can just fall out. get canned air or air hose to see if you can air the paper out of the points . indirect air should not be able to move the paper, its that close . dont use manilla paper nor business card those to thick. paper can be as tight felt as holding a potato chip. then time it after that. turn lights off when looking for spark and also hold the plug with hand pressure to non painted fin on your jug. one time mine was sparking and i was missing it because of the little things. then magneto connection black wire should be going into the black/white wire. if no spark unplug kill and confirm good ground at under gas tank coil . coil should be plugged into black or blk/white. also if you dont have battery in it be sure to tape up and unplugged wires to make sure nothing from harness is touching ground and grounding things out.

might help. helped me but i think my compression might be slack as im still not starting. i dont know how far you set the guage on a 100 but on 250cc its 3.2mm btdc. like in video i used an extra flywheel hub grinded apart so i could see what i was doing but someone on here said flywheel might vary so use orininal or check with original. i dont see how yall see up in the flywheel to set the points but i guess yall doing it since 69. anyhow wish you luck.

Get a feeler gauge, check gap, verify you have spark, then come back.

garyramir my 1980 DT100 has points because it's a Canadian bike. Yamaha did some weird stuff with models outside the USA.

Thank you for all the advice, I really appreciate it! Yamaha did some interesting things with its models across different markets. Mine is a 4L7 DT100X, introduced in Pakistan around 1980, with the last ones arriving around early 1983, as far as I know. It still has points ignition, although people do convert these to CDI, but the conversion is quite expensive here.

Mine has matching chassis and engine numbers, and its styling is quite similar to the bigger DT400 Enduro. Interestingly, I also have an exhaust from an early 1977 1X0 DT100X.

Pakistan actually had a pretty interesting trail bike scene in the late 1970s. From what I've gathered, the army used Honda XLs, there were Harley-Davidson SX models around, and quite a large number of DT100s were imported, including the newer monoshock models. A lot of those later ended up being converted to 175s. There were also a few Bajas and, apparently, even a container full of Kawasaki KE100s and KE175s. It's fascinating to think about how many of these bikes were around back then and how few original examples seem to have survived.

Right now, I'm trying to bring mine back to life, but importing parts into Pakistan is expensive, so I'm making do with whatever resources I can find locally. I'm even working on designing an expansion chamber for her, which has been quite a learning experience! I still need a fair few parts, and I'm waiting for some bills to clear before I can finally send the engine to a mechanic and get everything sorted.

If you ever have more information or advice about these old Yamahas, please feel free to email me. I might not always be active here, so you can reach me at This email address is being protected from spambots. You need JavaScript enabled to view it.. I'd genuinely appreciate hearing from someone with experience with these bikes. Thanks again!

share.google/VtButknsnRs8lTCoM this is what i own

You could guess the timing near enough to get a result of some kind & would either start or try to or kick back etc. Are your crank seals in place both sides, sorry to ask--but if it has fuel in the carb & has spark in the ball park she's gotta run or fart at least. Piston the right way around--skirt holes to the inlet side. Reed block not sitting on the bench. Crank key good. Timing at 1.8 btdc & gotta run. Apologies for asking dumb question--but i do that these days when all else fails.