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Big Bore Jetting and Dynatek DFS3-16 Non-Programmable CDI

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Hello and good morning!

I have been searching the web for awhile now and I can't find any good info on the Dynatek Non-Programmable box (P/N DFS3-16) for the DRZ400.

I received the box last night and plugged it in, and the bike idled just fine, but it stumbled from close throttle to WOT.

I assume this is because my FCR MX carb has no TPS sensor, and the CDI box uses the TPS to advance the timing accordingly.

Is there anyway around this for those of you who have used one? There is an extra plug available from the box, which I assume is for a TPS.

Anyway, after that, I plugged my stock CDI back in and was messing with tuning my carb, since my bike was running way too rich (to the point that the fuel mixture screw/Flexjet wasn't doing anything at all).

I was wondering if there is some generic settings for my carb that I can start with and then fine tune from there.

So far, all I know is I had a 188 main jet and I swapped it for a 165. That made it a bit better. I'm also on the second notch from the top on the needle jet.

I ran out of time, so I don't know what else is in there (pilot jet, etc).

This is my list of mods:

FCR MX 39mm.

Hot Cams Stage 2.

Cylinder works 434cc big bore.

Yoshi RS-2 full pipe.

3x3 mod.

Uni filter.

Located in Socal at about sea level.

Thanks so much for the help!

I appreciate it. :goofy:

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I have pretty much the same setup as you. Only diff, stage one hot cams and MRD exhaust.

I'm also at sea level. Sacramento.

I run a 155 main, EMN needle 3rd clip. It's perfect.

165 main is too big for a big bore.

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You can't expect much from the Dynatech, your oem ecu is probably better.

As JFM43 states, you are way off at your jetting, 155-158 mj is ok for your setup.

Tps sensor has no practical use in this bikes, you will not see any difference plugged in/out.

You should check which needle you have in your carb, there are a lot of examples of jetting in this site

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Thank you very much for the responses. I'll swap to a 155 next time I'm at the shop and I guess I'll just return the Dynatek box.

Do you guys like the E-model boxes?

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CDI is only gonna give you higher rpms. It's just going to put more stress on the valve train when you get to the rev limiter. I think you get 500 more r's from an E model CDI.

You're better off getting good quality valve work done than a CDI box.

Edited by JFM43

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CDI is only gonna give you higher rpms. It's just going to put more stress on the valve train when you get to the rev limiter. I think you get 500 more r's from an E model CDI.

You're better off getting good quality valve work done than a CDI box.

Doesn't the E-Model CDI have a different timing curve? Or is the difference just in the higher rev limit?

Also, what is a good source for valves?

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There is no point to having a your engine revving higher than stock cdi allows.....

The power has been, done and dusted by the time you're at the rev limiter..

OEM, Ferra or APE valves are good...you're in the US, I would give Eddie at SSW a call your performance bits and advice... 👍

Now that you have the dynotec cdi you might as well use it...it won't be causing your bog, it's just typical for an fcr to stumble when standing free revving...

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Doesn't the E-Model CDI have a different timing curve? Or is the difference just in the higher rev limit?

Also, what is a good source for valves?

The CDI's are identical between models except for the rev limiter. The rev limiter doesn't even give you 500 "more" rpm. The limiter has a hard limit rather than a "soft" limit. The E interupts more sparks quicker once it kicks in. My tach never reads more than 9900 as that's where the limiter kicks in and my tach counts sparks.

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There is no point to having a your engine revving higher than stock cdi allows.....

The power has been, done and dusted by the time you're at the rev limiter..

OEM, Ferra or APE valves are good...you're in the US, I would give Eddie at SSW a call your performance bits and advice... 👍

Now that you have the dynotec cdi you might as well use it...it won't be causing your bog, it's just typical for an fcr to stumble when standing free revving...

I'm returning the Dynatek CDI. It's not causing a bog at free revving, it's causing a bog from 4000 to 6000 rpm under load, in any gear.

I'm having a hard time finding a source for oversized valves, except for Kibblewhites which I've read are garbage...

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I'm returning the Dynatek CDI. It's not causing a bog at free revving, it's causing a bog from 4000 to 6000 rpm under load, in any gear.

I'm having a hard time finding a source for oversized valves, except for Kibblewhites which I've read are garbage...

Read line 3 , post #7

Use emn needle , clip 3

155 main jet

45 pilot jet, 2 turns fuel screw

200 main air jet

Remove pilot air jet

Do the o ring mod and turn the AP timing screw in 1/2 a turn...

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The CDI's are identical between models except for the rev limiter. The rev limiter doesn't even give you 500 "more" rpm. The limiter has a hard limit rather than a "soft" limit. The E interupts more sparks quicker once it kicks in. My tach never reads more than 9900 as that's where the limiter kicks in and my tach counts sparks.

This is something that has had me puzzled for months..... My Vapour often shows above 10k on the MR page (showing 10,040 ATM, I reset it each time I refuel). I have the tach wire connected to the spark plug lead so I assume it can only count sparks. How is it that my rev limiter allows me to over-rev the motor ?

OP, please forgive the thread jack :blush:

Edited by Mad Dogg W

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WARNING!!!!

Be careful with the jetting advice. As far as I know the 155MJ is a MIKUNI CV carb recommendation and the FCR MX is a KEHIN ( I stand to be corrected). The main jet sizes are not the same unit measurement. There is conversion tables available . One unit is size of the oriface, the other is flow rate.

Having said that: I am about to rebuild the motor with a 434cc kit. Has anyone recommendations for the Std Mikuni rejetting for the big bore? Preferably arrived at on a dyno.

Edited by gregjet

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lol2.gif......Before you go dishing out warnings you may wish to do some more research to gain a little more subject knowledge..

For you set up....Use a JD jet kit

At near sea level with BB, open pipe and 3x3 mod...

155 main jet

JD blue needle clip 4

22.5 pilot jet with extended fuel screw

2.75 turns

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I swapped to a 155 main jet and the bike feels great, thanks for all the help. I'll have to pull the carb soon and check the pilot jet, etc.

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Craig485sm.

I was not indicating that anyone was right or wrong for the recommendation on the jetting just a general warning to check the context of recommendations of jetting because of the differing methods of measuring the jet size. I have noted the tendency of contributors to quote jet sizes WITHOUT mentioning which carb they were referring to ( in this case you DID indicate) and in the drz context that is problematic, because there is such a large proportion of interchange of the Mikuni and the Keihin carbs on this model by modders.

I have been racing for years and been tuning and swapping Keihins and Mikuni carbs on many different bikes so I am not without some experience , though I would not class myself as a genuine expert .

My comment was also bourne of the fact I have been reading the Mikuni posts and pretty much ignoring the Keihin ones, which is why I said I was perpared to be corrected.

Thank you for the recomendations for the big bore . I will use these as my start point. The bike will be used on road by my girlfriend, so critical tuning won't be occuring, just a reasonable ballpark.

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The keihin and mikuni main jet sizes will be the same retrospectively......

Like comparing a 155 mikuni main jet in a stock mikuni carb V's a 155 Keihin main jet in a Keihin carb......... both mj's deliver the correct amount of fuel for the same engine mods..

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