c series pipe

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dsmitty
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c series pipe

Post by dsmitty »

Thanks for all the advice guys. The DG is the only one pipe I can find that is still made for my 1988. I was told it is tuned like the stock one. what about buying a Gnarly for a 89 (or E), cut the front end off and weld my stock on it to make it fit my motor? I think Ive done all the basic cheap mods but I keep reading about how much the Gnarly helps with the low and mid. Does a pipe help the c series bikes as much as the newer ones? I had mine bored, wiseco, boyesen 607 reeds, airbox lid, cleaned carb and jetted, cleaned and polished jug and head, 13/52 geard. We all love this old bike. It rarely goes over 25 mph. Sometimes 45 or 50 for a quick rip to the next playspot. All trails and shale pits with small jumps and hills. I wonder if another + - $275 for a gnarly pipe would make it even better for how we ride it. Thanks for any help or thoughts.
While Im at it.....Cylinder base and head milling
Something they do with the squish band?
Torque ring
Torque spacer
RB carb
Any of these worth the $$$$. Any other torque tricks?
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Julien D
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Re: c series pipe

Post by Julien D »

I'll let someone with more C series experience chime in, but I believe the DG pipe would be a big improvement over stock.
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dsmitty
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Re: c series pipe

Post by dsmitty »

thanks. LOL I think that means that the stock is crappy! thats great news cause we think the bike runs great as is. But if we are missing out on some good power and torque that we can get for a few $$$ is a shame!! Thanks for the help.
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Re: c series pipe

Post by KDXGarage »

Here is my experience with my 1987. I had Boyesen reeds, a Twin Air air filter and an Answer S/A-Pro spark arrestor. I rode that for a while before switching from the stock pipe to the FMF pipe. The pipe change made a bigger difference than the other parts. It had more power and a bit of a hit in the midrange.

By the way, I do not think that the FMF particular model was the Gnarly. The Gnarly is a thicker pipe than the Fatty. My pipe was "Gold Series" or :Gold Series Fatty" or something like that, I "THINK".

You already have the Keihin PWK35, so that is better than the Mikunis on the 1986 and 1987.

Stock gearing is 13/47. Since you have a 52 on there and are wanting more power, maybe a KDX250 or KX250 is what you need to try. Dirt Rider showed the 1986 KDX200 as putting out 24.x HP on the Kerker dyno. I don't think you will ever get it to make a huge amount of HP. Most 250cc MX bikes make low to mid 40's on HP. If you want power, see if you can test ride someone's.
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Re: c series pipe

Post by dsmitty »

Thanks Jason. I've got a 99 yz250 and a 88 cr500 and a 84 al baker xr500. The kdx was supposed to be a spare bike for freinds that I picked up for $300. I ended up riding it more than my others and so does everyone else!! The power (top end) is PLENTY for how its rode. Just that with the 13/47 set up, at 15 to 20 mph 1st was revved out to much and 2nd had the low end BAAAAAHHH bog until the mid hit but then we were going to fast for our tight jumps and hills. I'm trying to get more low end so I can putt around with taller gears and not have to downshift. Even with the 13/52 it still bogs a bit when giving it gas at a putt speed or revs I should say. When we go for long rides the motor is workin a bit at 50 mph but that is rare and i use my xr. Thanks for the input!!!
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Re: c series pipe

Post by Julien D »

I think you'll find that the DG will add power overall. If I'm not mistaken, your stock pipe is double walled, and so it has a fairly small internal diameter as compared to a single walled aftermarket pipe.
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Re: c series pipe

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thanks, i just talked to the guys at dyno port and guess what, 89 and later. anybody tried the cylinder and head milling and the squish band thing. Porting and all that. I've mostly heard up to now that it's not a good bang for the buck mod (for torque) and it hurts reliability. What about that moose racing torque spacer and the torque ring. I think I read that the dg pipe is fairly inexpensive. the dyno port guys said for slow bottom end riding pipes dont make a big difference. He said to weld a 1/8 to 1/2 inch extension onto the 1st 12 inches of the pipie for as much noticable gain in low end torque as a new pipe.
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Re: c series pipe

Post by Julien D »

I will respectfully disagree with the dynoport guys. Pipe choice makes a huge difference on a two stroke both bottom and top end. I personally wouldn't mess with porting and head milling on an 88 KDX, but it just depends on how far you want to go. I would certainly swap the stock pipe, make sure the airbox is opened up, and jet it spot on before doing anything major. Those simple things alone will make a huge difference. For what it's worth, I run a DG pipe on my 89, and it is night and day over the stock pipe.
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Re: c series pipe

Post by dsmitty »

Thanks again Julien. I think I agree. This was intended to be a cheap spare bike! but we, the kids 16, 22, 23 yrs old and myself ride it more than the others! At least just for gooffin off which is 90% of our riding. How much $$ does one want to put in an aircooled 24 year old bike! And on THIS bike is it worth the gains with regard to reliability. So will it be ok to just bore it without that squish band work. A lot of guys tell me to do the squish when you bore it.
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Re: c series pipe

Post by Julien D »

Does the cylinder require a bore at this point due to damage/wear, or are you just looking to gain power by going with a larger bore? Unless you are sourcing a big bore kit for it, there's not much noticeable gain by going up a piston size or two.
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Re: c series pipe

Post by KDXGarage »

Who is doing the boring work?

What diameter is it going to be bored to?

What about the power valves?
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Re: c series pipe

Post by dsmitty »

thanks guys, you are really helping me out. Hopefully others too. the bike ran ok when we first got it home. I put a 52 sprocket on the back and Took it up to the mnt. for a day to check it out. WOW! Mouse nest in airbox, filter fell apart when i touched it, ran hot. I know, could be a lot of things, hot plug, mix, jets etc. Got it home and took it apart. Cleaned the chit out of everything and made an air filter. Piston is scored a bit and cyl. wall has minor score matching the piston. We were running it for a while like this but the heat got me worried Ya, I don't want an overbore, only enough to "fix" it. I can't find a machine guy around here that I like, so I want to send it out. Fredette or eric gorr i guess. The current piston says 75.5 mm. The power valves appear to work good. So I'm hoping that the bore w a new piston, boyesen 607 reeds, new jets should do the job. Maybe try the torque ring and/or spacer. Im really wondering about Ron Black's carb work. What do you guys think?
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Re: c series pipe

Post by KDXGarage »

You made an air filter??

The piston diameter is 75.5?? Stock is about 66.

Is it plated or sleeved?
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Re: c series pipe

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Somethin is weird here. My piston says 71.95 mm. What the heck? Is this one of those Gorr 240 big bore jobs? I dont know a lot about sleeves, plated and all that. It has a sleeve lookin thing in it and my buddy says its a sleeve. LOL sry. I think I should just send the whole top end to Fredette or RB. Maybe runnin hot cause cyl. walls to thin from the bore? Yup, screw it, i'm sendin it out. Any recomendations without gettin in trouble??
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Re: c series pipe

Post by KDXGarage »

Can you post pictures?

Does it have a power valve system?
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Re: c series pipe

Post by dsmitty »

LOL i gotta wait till my daughter gets out of school!! I'm too old to know how to do that!! Ya I got powervalves, they appear to work properly. There is no way a 71 mm piston could fit into a jug made for a 66 mm. Thats the piston that was in it and we were runnin it. Something isn't right. I just measured it with a ruler and it's just under 2 and 3/4 inches. :) it is an old wood ruler from before they put metric on them. I wonder what in the heck the displacement is.
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Re: c series pipe

Post by dsmitty »

I just found out it is a 240 big bore kit from LA SLEEVE. Oh boy, is this good or bad? ya a little more power but heat, reliability and longevity? Eric Gorr says he has a stock jug he will throw in for free if I have him do the work. Go stock or keep the big bore kit. LA has a 72.5mm wiseco if the current sleeve needs bored.
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Re: c series pipe

Post by KDXGarage »

What work are you talking about Eric Gorr doing??
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Re: c series pipe

Post by dsmitty »

Since it is the big bore kit, who knows who did it. Are the ports right? head-squish? I gotta figure how much $$ I want to spend. Mandatory is, 72mm piston $175, Gasket set $70, and bore job around $80. So $300-$350. Shipping,tax, etc.

EG says $500 (plus shipping) gets the whole package. Jug ported, polished, bored and machined. Head work, powervalves, piston, gaskets, and all that other stuff he does, diamond honing, baking soda blast etc. No brainer? $150-$200 more for all that? I already bought the twin air filter, boyesen 607's, DG pipe, chain, sprockets, knobby. So much for my $300 spare bike! LOL. It's all good, the kids and I love the bike. for the three weeks I've had it, they rode it more than their own bikes before I took it apart. CRF150 and TTr230. I have a 84 al baker xr500 and a 88 cr500 and love the kdx just as much, aircooled and all. Fits right in. Any ideas or thoughts? Is the kdx bottom end, tranny and clutch gonna handle all this? Geeze if i'm spending all this $$ I should get the RB carb mod too. Maybe a gps, cruise control and airconditioning. Don't they make gold plated gas caps for the c series?
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Re: c series pipe

Post by hbgod »

i just had my 86 sleeved, bored (to stock), and ported. just got a pwk35 in and sending off the rest of the motor. getting dyno tuned as well so ill let you know when i get it all back hopefully soon.
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