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Makotosun

DT400 75 settings

  • Paulfb
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DT400 75 settings was created by Paulfb

Hello there!
New on this nice and helpful forum, I’m spending lots of hours on my bike to try to set the engine properly.

Bike is in good conditions, 6000km, no big modifications.
Fresh gaz, need oil in both case and tank.
Cleaned carb, needle 4th clip, main 160, pilot 40 & floating 25.

Thinking my pb could come from the ignition as it’s in very bad condition.
The stator was set full left side (see pic)
I ll try with an other ignition coil today!

Thanks for your advices!
Paul

04 May 2020 22:38 #1

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Replied by MarkT on topic DT400 75 settings

From what you said in your other post about running very rich it sounds like maybe the jet setter o-ring is not sealing into the bottom of the float bowl.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
04 May 2020 23:20 #2

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Replied by Gr8uncleal on topic DT400 75 settings

Could be the CDI broken (pulser?).
05 May 2020 01:29 #3

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Replied by Pedalcrazy on topic DT400 75 settings


The DT400 doesn’t have the jet setter o-ring in the bottom of the carb like the earlier DTs and RTs.
1978 DT400E
1976 DT400C
1973 RT3
1971 RT1B
1968 DT1 (3)
The following user(s) Liked this Post: Bigdog302
05 May 2020 08:32 #4

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Replied by MarkT on topic DT400 75 settings


Thanks for the correction... my 75 DT250 has the old style even though it's a spigot mount carb. I looked at the diagrams and you are correct, the DT400 doesn't have the jet holder in the float bowl.

:likey
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
05 May 2020 09:15 #5

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Replied by run103 on topic DT400 75 settings

So what exactly is the problem. Does it run at all If not does it have spark. If it has no spark it is probably the pulser . Get an OHM meteer and test the 2 leads on the pulser and it should be 90 ohms give or take 5%. If not the bike will not run
Doug
05 May 2020 10:36 #6

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Replied by Paulfb on topic DT400 75 settings

Yes the bike starts easily, 1st or 2nd kick, idle at 1500rpm.
When I turn the throttle on, the engine struggle and can’t reach more than 4500 rpm, with detonations from the exhaust.
The acceleration is not “natural” sort of 4 stroking, not linear and while riding, a real lack of power.
05 May 2020 13:55 #7

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Replied by run103 on topic DT400 75 settings

Does it ever kick back when starting. Ive done 16 of these restores to be riders and i have had one bad spark plug coil and no bad cd boxes and several damaged pulsers. Some kick back and then run for a while and then when they get hot they quit when your 10 miles from home. Some just give intermittent backfires and never start. some just never start. Your pulser looks like it easily could be damaged. The problem is when you first pick the bike up it looks in nice shape for the age so you kick it over to see what the compression is like BUT the problem is the stator area is full of debris and rust and dirt and the garbage gets pinched between the flywheel magnets and the pulser and it breaks the fine wires in the pulser and its done just that quick. If you clean it before you kick it over you probably would have been OK. Once cleaned and kept clean i have not had a pulser failure
Doug
05 May 2020 14:15 #8

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Replied by RT325 on topic DT400 75 settings

Welcome. Looking at the stator plate i'd call 'that' full right not full left, but no matter. That's as advanced as the slots will allow, but if it starts ^ runs without kicking back big time then it's sort of ok even if more advanced than specification says. So--i'm stuck on blocked or very restricted exhaust spark arrestor burried way down in the tail muffler. That'll kill any power up in the revs & make it limit out & 4 strike like an over-rich main jet. & when you pull the muffler, look down in where it engages as grow carbon where that pipe ends in the main chamber. Sorry but lately i seem to be stuck on that [blockage] answer to so many questions.
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05 May 2020 16:16 #9

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Replied by RT325 on topic DT400 75 settings

Re-thinking my answer i 'did' have a faulty pulser on a DT360A years ago but was faulty on the starting half so wired it so it started on advance & worked good, just had to kick it right to avoid getting kicked back. But--thinking on those lines i wonder if the pulser was faulty on the advance side as flicks up at about 1000rpm [guessing], mind you if it was faulty it might start but be limited to idling [even on full song] so i'm guessing yours is getting way above that!!--i'll have read later.
05 May 2020 16:24 #10

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