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Trx 300 CDI interchange & mods

54K views 41 replies 12 participants last post by  3126 kitty cat 
#1 · (Edited by Moderator)
A lot of CDI talk again lately, thought this would be better for future searches. Other members, add what you know so we can all turn back here as a reference point :)

My understanding so far is that gen1 and gen2 wiring harnesses can be used with gen1 and gen2 CDI’s. Gen3 can’t be as the plug is completely different.
So, gen1 is 88-92, gen2 is 93-97 & gen3 is 98-00.

How to identify your Cdi.

With the Cdi removed form the machine, stand the cdi upright with the plug facing you.(Edit: plug at the top) 88-92 will have the plug set to the right of the box, 93-97 will have the plug set to the left of the box.
98-00 I have seen two different types, one with wires coming from the Cdi to a plug, wires and plug are a total of around 3”. The other type just has a plug on top of the Cdi. The plug (on both 98-00 types) is noticeably different to the Gen1 & Gen2 varients, a bigger plug, more pins and more square in shape.

Gen1 Cdi’s Have a more advanced timing curve giving a little more throttle response, where as Gen2 and Gen3 have a slightly lower timing curve resulting in slightly less throttle response.
Reputable tuned Aftermarket Cdi’s Are only available to fit Gen1 and Gen2 wiring harnesses, they aren’t made for the Gen3.
Stock replacement Cdi’s are made for all 3 generations.

Gen3 wiring harnesses can be fitted with a 350 Rancher Cdi, power gain results I’m unsure of but being from a bigger CC machine I should imagine there are some noticeable gains.
The only other alternative to getting a tuned Cdi for a Gen3 is to swap the wiring harness for that of a Gen1 or Gen2.
 
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#2 ·
Good stuff ! you are right , there has been a lot of CDI problems lately

Be careful with counterfeit CDI's , seems there are a lot of them going around on e-bay , Rick's CDI is the brand that is being faked ------ been told the Rick's has manufacturer codes engraved into the casing , even though I have a Rick's on mine , I can't confirm that as I didn't pay attention to the code before installing as I didn't know about them , I know I have the real deal as I used a Tiny tack to check the rpm's before and after the change , the OEM 95 300 turned 6k with OEM CDI and 7K with the Rick's , I bought it over the phone from Rick's direct so as to get the correct one for my year and do not purchased off e-bay ----- If you were going to buy a Rick's CDI , I would only do it over the phone and not on-line
 
#3 · (Edited)
Thanks Sam
I didn’t get earlier refs to Gen 1, 2 and 3; clear for me now.
Honda fiche list different part numbers for 93, 94 CDIs—but are they interchangeable within the Gen series?
What are the different codes for? Here are three on is a 93 the other two are 94. All made by Phillips
 

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#4 · (Edited)
I can’t find out any information relating to part numbers within the same generation. I do know that all Gen1 & Gen2 Cdi’s Are interchangeable though.
If anybody can find out what the difference in part numbers is I’d be interested to find out.

Edit: Wondering if the part number differences would be for cooling fan control, one with and one without maybe?
I will email Ricks and see if they will share any info on the part numbers.
 
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#5 · (Edited)
Mister Rick himself spose to be back @ the end of this week ,I'll be bellsouthing him, this is what they told me, referring to the option ( @wheelers string) on the ricks cdi for a rancher nether one 15620 or the 15621 is a ricks hot shot performance cdi, BUT might, n yes might could be wired to 98-2000, 300 2 or 4 wd, the only dif is the 15621 has a cooling pigtail wire, that's all i have for now....

.we're un covering all the stones on this cdi deal!

:edit this page

http://www.hondaatvforums.net/forums/builds-projects-diy/81890-operation-big-bore-8.html
 
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#7 ·
So, my mind has wandered back to the realm of CDI’s...!

I had a thought. As we established in previous posts, the TRX250a and 300fw share many engine parts, including the cam in Gen1 models.
Is or would the CDi be the same? The plug fitment is the same as Gen1 and gen2 300’s, I’m considering plugging my 250 CDI into my 300 to see if there is any improvement or noticeable gain.

Mentioning @retro & @fishfiles here as you guys are knowledgeable with these models and take an interest in my odd theories! Lol.
 
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#8 ·
I can only think of three ways to figure that out Sam , find and talk to some one who has done it , talk with Honda's engineers or try it and see what happens and hope for the best Columbus took a chance and it worked out for him , LOL -------- someone who is well versed in the electrical system of the two models , with a schematics could possibly say if it could work
 
#10 ·
I’m wandering if it is the same CDi as the Gen1 and Gen2 300’s if it is it would explain the three part numbers.
 
#12 ·
I can tell you this, oem c.d.i.'s from Honda have a white connector on the back, where is aftermarket seems too have a red connector on them. unless Honda changed thier connector colors ?, then this is a dead give away.
 
#13 ·
All my gen2 CDI’s are the OEM Philips varients one is white, the other green. The 250 I think is also green, I’ll need to check that to be 100%. Maybe green is a UK thing?
 
#14 ·
they made the oil temp controller/alarm connector green, but the c.d.i. connector part is white on all oem c.d.i.'s from Honda.
 
#15 ·
Pics of OEM 300 Gen2 cdi show red plugs. Shade, you were right with green being the alarm box plug. My Gen3 cdi is black and the spare I have has a white plug, both are OEM.

The other two pictures are of 86 trx250a cdi, i have no idea what an OEM looks like but at a guess mine doesn’t look OEM. The name maybe a dead hive away?!
If this isn’t OEM it looks like it’s been changed prior to my ownership.
The plug however is white, on the harness plug is HA-8, I’m assuming that is the model of CDI that would be fitted from factory?

Can anybody confirm what number is on an OEM stock 300 Gen1 CDI?
 

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#16 · (Edited)
I have never seen a red c.d.i. connector on an oem c.d.i. from Honda on a trx300 ??, all years were white, and Honda did not stamp letters and numbers on the c.d.i. , just the connectors.
 
#19 ·
So looking at Sam's original post...

I have a 90, an early 93 (first gen frame), a 95, and two 97's.

I will probably keep the two 97's and maybe the 95, and fix the 90 for a friend of mine's kid. The early 93 is basically a parts bike.

With that in mind, I can use the early CDI's off of the 90 and 93 on the 97's, and put the lower RPM 97 CDI on the 90 that the kid will be riding, right?
 
#20 · (Edited)
Yep! It wasn't until 98 that the CDI pin count (5 vs 6) were changed, so all 300 CDIs 88 thru 97 are plug & play interchangeable. The 1st gen CDIs allow the motor to rev a bit better and make more power than the others, so you are spot on with your plan...

See the attached images for the CDI plug wire color change going to the diode and starter solenoid. As far as each CDI plug fitting every wiring harness ever made...? I have no idea. But CDI pinouts are the same, so the plug doesn't matter...
 

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#21 ·
Maybe I'm not reading that right, but it looks like the wires all go to the same components, but it also looks like the wires go to different spots on the CDIs depending on gen.

The bookface crowd said they wouldn't interchange. Your diagrams appear to prove that incorrect, but to make them work will I have to cut the Gen 1 plug off the wiring harness and splice it onto the Gen 2 harness to get this to work?
 
#22 ·
I'm not sure how many different CDI plugs were used through the years, if any..? If you have some with differing plugs then the plug would have to go with the CDI being swapped. I'd just move the wire colors to the proper order in the plug if you know the order they should be in.

That is one of the things I intended to research when Sam started this thread, but I don't have all of the various CDIs and harnesses on hand. On paper they should swap, but in the real world...?
 
#24 · (Edited)
Same here, but i still plan on a cdi mod/swop, after we can get this plug and play figured out, I'll be glad when @SamUK comes back in on this topic, and would be glad to have him back n the forums.....
 
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#25 ·
From my understanding there was one cdi made for 1st gen, and 2 or 3 for 2nd gen, I have two for a second gen and have ran both since my absence with no issues. I’ll take photos, there are numbers but I can’t remember off hand what they are.
 
#28 ·
Something that recently came to my attention... Some folks claim that a 1st Gen wiring harness CDI plug are different to a 2nd Gen plug. I have both and both of mine fit 1st Gen and 2nd Gen CDI’s. Can anyone else confirm this?
 
#29 ·
We learned that the wire colors in each plug remained the same from 88-thru 97, but cannot verify whether all of those CDI plugs are the same shapes or not. Also not 100% sure whether each plug has the same exact pinouts or not. On paper (service manuals) they should all be interchangeable. I would verify that each wire color is in the right location inside each plug before attempting a swap, just in case.

Maybe you can now... since you have a 1st gen CDI & harness handy?
 
#30 · (Edited)
#31 ·
I’ll get some photos of harnesses and CDI’s together and add them later on, I’m sure we can figure this out :)

Yes, I’d heard of the 350 Cdi being used, seems quite a few use them over the pond there.
 
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