replacement rods??

mgtkr1 · Post by **mgtkr1** » Tue Jun 09, 2009 7:58 pm

what other rods will fit the kr? im sure i saw a thread that mentions kx125 rods. also thought about using a 54x54 b/s as i read somewere on here something similar. we all know its the best configuration ideally for best hp/midrange ect. a zeeltronic setup is on the cards but have been toying with the notion of having a 4dp crank end mated to a spare crank when i have one rebuilt aswell as getting dad to make a backplate allowing me to run a tz ignition/smaller rotor. not that it will make me faster, just enjoy the idea of fettling the kr. prob just anotherr pipedream but wondered if anyone has considered it seeing how the std ignition is crap. advancing the static timing seems to sharpen things up a bit but still, the cdi decides its game over very early on. think it was twostrokeinstitue who suggested 54x54.

KR-1R · Post by **KR-1R** » Wed Jun 10, 2009 1:33 am

online investigation on the 1990 H1 KX125 rods = 50.6mm stroke
reveal same part no. 13044-5071 as KDX200-G5 (same as 1989 G1 KX also) at cost of 8421YEN
(includes conrod,crank pin, bearing, thrust washers (22.2X37X1.0))
I havent got either KR or KX motor in pieces to say if bearing diameters are the same - the gudgeon are different part numbers.

the whole KX crank assembly at US$280 if you were tempted to make a tandem twin 50.6mm out of KX

the adventurous would go the 54mm route if only because of selection of compatible parts still available.

TwoStroke Institute · Post by **TwoStroke Institute** » Wed Jun 10, 2009 2:00 pm

Unless you want to burn some cubic $$$$ forget the 54 X 54 crank.What seems to be the KR-1's crank achillies heels is those stupidly thin thrust washers. Then there is the pistons that belong in a trail bike. I'll be rebuilding my crank with some air cooled RD 250 110mm rods with Cagiva Mito SP flat top pistons.The reason for the RD rods is they have a 28mm big end eye and a 20mm small end eye.The 28mm big end can take a 18 roller cage(same as a TZ) and the small end a 14 roller bearing.More rollers , more contact area = more rpm all for the price of a rod. I am not sure if the KR-1 has a 105,106 or 109mm rod but the longer the rod the better. They look to be 105-6 to me which should mean the same installed height so no machining off the base of the cylinder, all the work will be in the cylinder head, with this modification
When PJME pull their finger out and offer just the crank seals, I can split the crank I have here and start to sort this, I might have to machine off the webs to fit 1-1.2mm thrust washers, although the RD rod is 16mm wide and may allow the swap with no machining at all the verniers know the answer there. A press out crank pin with a radius might be preferable to the integral pin also.
This is the stator rotor you want to go for, as if you run a 4DP stator you will have to run a 90deg crank(which you should be thinking about anyway, but that's another topic in itself)

the-elf · Post by **the-elf** » Wed Jun 10, 2009 3:20 pm

I have a crank sat in my garage with KDX rods which are roughly 2mm longer than the standard KR1 ones. The cyinder head had been machined to take the longer con rods. The only drawback I can see is that your going to mess up the port timing unless you fit shorter pistons or thicker base gaskets to compensate for the rods.

mgtkr1 · Post by **mgtkr1** » Wed Jun 10, 2009 6:05 pm

what ignition is that in the pic? sorry, not 4dp. it was a unit off one of ther reverse cylinder bikes, 250u ect. 4dp popped into my head purely spur of the moment. discussed it breifly with someone a while back. also heard of an alloy rotor with the std pickups bonded in somehow. tried to get em to part with it but was having none of it!! like me, i guess anything intresting is worth keeping. has anyone actually found a rotor of a mx bike that physically fits?

TwoStroke Institute · Wed Jun 10, 2009 10:04 pm

The Mito Sp pistons have shorter comp height, even if you have a longer rod and set TDC to 0.00 deck height the port timing will be basicaly(less than 1 deg difference) the same.KDX rods are 109mm so my guess was 106mm for the KR so that might not be far off.The stator rotor pictured is the same as what will be used on the TSS 500.

the-elf · Post by **the-elf** » Thu Jun 11, 2009 8:42 am

Sounds good. I might look at using the Crank with the KDX rods at some point. Are the Mito pistons simular to the TZ single rings?

Sorry if it shows it in any of the pictures but I'm away working ATM and the company block stuff from sites such as photobucket, so I can only read the text.

TwoStroke Institute · Post by **TwoStroke Institute** » Thu Jun 11, 2009 2:00 pm

The RD rod is far superior to the KDX, plus you will have a 2mm(rather than 1mm) shorter installed height of the piston/rod assembly.Also the RD rod big end width is 16mm wide as compared to the 17mm KR which means the thicker thust washers will just pop straight on.The Mito SP piston looks like THIS about half way down.The Pro-x looks like the pick of them, the Mitaka has a close up of the piston.

the-elf · Post by **the-elf** » Thu Jun 11, 2009 3:32 pm

you've got me interested

I'll take a good gander at the pictures when I get home tomorrow night.

mgtkr1 · Post by **mgtkr1** » Fri Jun 12, 2009 5:06 pm

in relation to the ignition, i stumbled upon this. wonder if they would make one up to fity the kr's crank taper?? also not sure on prices yet but are supposed to be a good unit. used in icgp on the tz's ect.

http://www.hpi.be/universalignition.htm

TwoStroke Institute · Fri Jun 12, 2009 10:56 pm

The HPI ignition looks remarkably similar to Electrex stuff from the UK.
Compare the 3 cylinder ignition from HPI to THAT from Electrex.No prices on HPI which is(like any restaraunt) a bit of a worry.Who is going to send the email to HPI?

mj43 · Post by **mj43** » Sat Jun 13, 2009 7:33 am

I read it that Electrex are UK agents for HPI

mj43 · Post by **mj43** » Sat Jun 13, 2009 7:37 am

I read it that Electrex are UK agents for HPI