88 Honda CR250 Hybrid kicker

wolfy0067
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wolfy0067
Edited Date/Time 8/27/2018 8:26am

Got a call from a buddy, found this 88 cr250 in a barn, had been sitting for almost 20 years. Well I couldn't resist, so I took it off his hands at a reasonable price including new water pump cover, pump shaft, seals, radiators and PC exhaust. everything is very tight, still had the original front tire, however air box and filter were never sealed causing the cylinder to chip at the exhaust.

Disassembled the top end. Chris Ray at Power Seal did his magic recoating the cylinder, honed to a perfect 40 degree cross hatch to the coated surface.
Before just assembling the topend I wanted to make sure to tolerances meet the specs I was looking for, I had planned modifying the head and cleaning up the cylinder.

2mm squish clearance, setup for west coast gas? this will need to be adj in the range of 1.4 for a 250cc, head volume will be in the 21 to 22cc range.

Over to my porting bench started working on cleaning up the exhaust then the intake has a lot of casting slag.











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wolfy0067
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wolfy0067 12/7/2015 8:42am
12/7/2015 8:42am
two different styles of measuring the squish clearance to make sure all is correct





wolfy0067
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wolfy0067 12/7/2015 8:53am
12/7/2015 8:53am Edited Date/Time 12/7/2015 9:53am
Worked on the exhaust port Sunday, matching the flange smoothing then polishing. Next is the intake needs to have some of the casting slag removed then smoothed . Transfer ports are real good on Honda's no need to touch them at this point.







wolfy0067
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wolfy0067 12/7/2015 9:33am
12/7/2015 9:33am
I like to use this method of holding the piston till assembly time, can be used to get the piston started on the jug also
works great for holding connecting rods.

1
wolfy0067
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wolfy0067 12/7/2015 9:54am
12/7/2015 9:54am Edited Date/Time 12/7/2015 9:55am


Wanted to get a better photo of the casting and slag sticking into the boost ports, left side wasn't even cleaned up after casting.

The Shop

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MR. X
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MR. X 12/8/2015 7:46am
12/8/2015 7:46am
wolfy0067 wrote:
I like to use this method of holding the piston till assembly time, can be used to get the piston started on the jug also works...
I like to use this method of holding the piston till assembly time, can be used to get the piston started on the jug also
works great for holding connecting rods.

That's a wise use for some old power bands that would otherwise just lay around. Looks good!
ATKpilot99
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ATKpilot99 12/8/2015 7:52am
12/8/2015 7:52am
Where are all these barns ? lol
wexy21
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wexy21 12/8/2015 10:29am
12/8/2015 10:29am
That's awesome! Nice to find another 88 barn find here. I found mine in a basement after sitting for 26 yrs. Basically was ridden the summer of 88 and then sat. The tires even had cob webs inside them!





I've since taken all the plastic and tank off and put them away, buying new so that I can ride without hurting it much.
wolfy0067
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wolfy0067 12/8/2015 10:45am
12/8/2015 10:45am
Very nice bike you scored there, still has the stickers on the fender, mine has more corrosion from sitting than wear, talking about tanks, I worked a deal and scored a VRP tank and sub frame, along with a rolling 89 frame a friend is giving me for free.

Just watch the cooling issue, mine was totally blocked, needed new pump cover and radiators, just need to get my head modified and then finial assembly
RyanLester761
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RyanLester761 12/8/2015 10:54am
12/8/2015 10:54am
wexy21 wrote:
That's awesome! Nice to find another 88 barn find here. I found mine in a basement after sitting for 26 yrs. Basically was ridden the summer...
That's awesome! Nice to find another 88 barn find here. I found mine in a basement after sitting for 26 yrs. Basically was ridden the summer of 88 and then sat. The tires even had cob webs inside them!





I've since taken all the plastic and tank off and put them away, buying new so that I can ride without hurting it much.
Such a clean bike! Are those Kawasaki fork guards bolted to the lower triple clamp??? Very innovative if so!
wexy21
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wexy21 12/8/2015 11:08am
12/8/2015 11:08am
Yep...mine had more corrosion than wear too. The water seal and cover was ruined and the oil and water basically was evenly mixed after sitting that long. I had to replace those and then do massive flushing. I got the radiators clean which was surprising.

The fork guards are 92 KX's and the front plate from a 91 CR. I just hear molded the bottom of the plate to form around the slides then bolted together. Works well and looks a bit factory.

The bike has never been jumped or ridden in a track before so the suspension was a bit squeaky. Everything works like new though!
wolfy0067
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wolfy0067 12/8/2015 11:43am
12/8/2015 11:43am
Ya, that front plates pretty cool, I got luck in the shock dept. also, came with a Race Tech modified shock out of gas and bottoming bumper gone, a friend gave me an 89 shock modified to match Factor Connection valve stack.

Didn't ride it yet but should be good, forks are going to need rebuilt not sure what route I'll take yet, gold valves, 89 triples with a more modern fork, would like to go 2008 450 forks need to do research.

Always fun to take a vintage bike and add some modern parts.
wexy21
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wexy21 12/8/2015 2:00pm
12/8/2015 2:00pm
That's the issue I've been having with mine, wether or not to keep it stock. The fork boots are also tucked away, and those sliders can easily come off, but I still don't know how much I want to tear into this bike. my fork seals and suspension is good and I did buy a cr500 rear spring which would be more for my weight, but I'll paint it red to keep it looking stock.

if I keep riding it often it will need rebuilt eventually (never been a part yet) so maybe then I'll go with some aftermarket parts like exhaust and intake, etc. Right now it's fast enough! lol. I wish my original tires were still good, they rotted from being flat even though there was almost no wear on them.

I have a tecnosel seat cover to go onto my extra seat I bought and put all period correct factory graphics on the plastic. Soon as EVO gets back to me on the camel supercross (blue and yellow) #1 plate back grounds I'll have a pretty complete and nice looking racer. (I know the blue and yellow wasn't until a few years later).

It would be interesting to keep each others posts updated with our progress, and anyone else who has an 88 should post up as well! I love seeing the others out there!



original bar pad
wolfy0067
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wolfy0067 12/11/2015 3:35am
12/11/2015 3:35am
Cylinder is back in place power valves timmed, will work on the head this weekend



wolfy0067
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wolfy0067 12/14/2015 3:41am
12/14/2015 3:41am
Update, got the head done saturday got the squish down to 1.3mm these heads are not easy to cut with the angled plug





TTperra
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TTperra 12/14/2015 11:33am
12/14/2015 11:33am
Do you have a picture of the fixture you use in the lathe?
wolfy0067
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wolfy0067 12/14/2015 1:22pm
12/14/2015 1:22pm
It's a modified thread chaser, does great for holding heads, i also use a piston stop to chuck heads up with straight plug holes.
wolfy0067
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wolfy0067 12/19/2015 1:40pm
12/19/2015 1:40pm
The old barn bike is starting to come around, not a frame off due to bike being in good condition, not sue though, plastic tank and steel frame or VFR see photos. Also if VFR where do I get a cap and fuel valve
Thanks









wolfy0067
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wolfy0067 12/30/2015 3:57pm
12/30/2015 3:57pm
Put the finial touches on the 88 CR today, not a full frame off but all mechanicals are upgraded and ready for moto, can't wait to wring this thing out



Pit Row

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TTperra
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TTperra 12/31/2015 1:04am
12/31/2015 1:04am
Looks nice!

Still curios about the fixture, not sure how they look or how you modify it..
450exc115
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450exc115 1/1/2016 5:00am
1/1/2016 5:00am Edited Date/Time 1/1/2016 5:01am
TTperra wrote:
Looks nice!

Still curios about the fixture, not sure how they look or how you modify it..
My guess is that it a spark plug tap and he machined off the square head to make a nice round surface to grab in the lathe chuck.

Makes me want to get back to perusing a bench top lathe to go with my bridge port. Smile

Sharp bike and nice work on the motor.
TTperra
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TTperra 1/1/2016 5:26am
1/1/2016 5:26am
TTperra wrote:
Looks nice!

Still curios about the fixture, not sure how they look or how you modify it..
450exc115 wrote:
My guess is that it a spark plug tap and he machined off the square head to make a nice round surface to grab in the...
My guess is that it a spark plug tap and he machined off the square head to make a nice round surface to grab in the lathe chuck.

Makes me want to get back to perusing a bench top lathe to go with my bridge port. Smile

Sharp bike and nice work on the motor.
Yes, that will work with a head that have spark plug straight, but if it´s angled you have to set up the tap angled and offset to get the head centred, and adjustable so you can do different heads, steady also you don't want any flex..

Wolfy: Is it something like this you modified?



wolfy0067
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wolfy0067 1/1/2016 2:23pm
1/1/2016 2:23pm
It's just a plug tap modified to mount on an angle to off set the angled plug hole, I also use a piston stop, but a modified spark plug works I also have spacer and set the head up on a flat plate for the xmgled Honda heads, depends on what I'm trying to do, for straight plug heads to piston stop is quick and easy to setup
TTperra
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TTperra 1/1/2016 3:52pm
1/1/2016 3:52pm
Ok, I thought about flat plate and studs/spacers also.
Its for a CR480 head and CR250 -80 if it needs work, on air cooled heads you have the fins who doesn't makes it easier..
450exc115
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450exc115 3/22/2017 12:55pm
3/22/2017 12:55pm
Dave,

Wanted to ask you about your motor build as I'm digging into my 91 now to prep for the season. I noticed that my piston partially covers the transfer ports and being an engineer by trade thought this wasn't great for air/fuel charge transfer and wondered if you saw the same on your build. I'm not sure how I would correct it as it looks like I'd have to use a lot of gaskets to correct it. The easiest way is either epoxy it up which I'm not crazy about or old school trim the piston to match.

Thanks
Tom
wolfy0067
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wolfy0067 3/22/2017 6:05pm
3/22/2017 6:05pm
My cylinder matched up perfectly, however I have seen this before, at bottom dead center port flow is at it slowest speed, if your Dudu like me it has to be matched. You have a couple option. Not seeing or measuring the amount the piston to port mismatch I would probably, look at a bit of epoxy, a spacer plate cosmetic makes them, and cuttinthe piston crown. What piston are you using now?
450exc115
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450exc115 3/22/2017 8:05pm
3/22/2017 8:05pm
This is just how I found it. It's a cast piston with "ART" cast in the side.



I was hoping to just do a tear down and clean/paint refresh but I found this and I'm not sure what to think. Sad




It does have a "hot rod" rod in it so it appears that the crank was rebuilt.
wolfy0067
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wolfy0067 3/23/2017 1:52am
3/23/2017 1:52am
Something is deffently not correct, tear it apart
I would get rid of the wisco rod and replace it with a prox, would be a good starting point.

Does the head show any indication of the piston kissing it at high rpm
wolfy0067
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wolfy0067 3/23/2017 3:58am
3/23/2017 3:58am
Getting a closer look at the crankshaft, Holly smokes looks like someone took a hammer to it. I bet is so far out of tollerence.
450exc115
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450exc115 3/23/2017 7:02am
3/23/2017 7:02am
After some digging it turns out this crank has some tin/sheet metal stuffers over the crank halfs. I'm guessing the tooling used to install the rod was over tightened and crushed the stuffer. I still need to do some investigating but all may not be lost.

Dave the dome looked fine as did the cylinder. It had some cold seizure lines on the intake side of the piston but nothing transferred to the cylinder. The piston and crank look like recent work. Tolerate on the thrust bearings was .016"
wolfy0067
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wolfy0067 3/23/2017 9:39am
3/23/2017 9:39am
Do yourself a favor split the cases, check the run out, When rebuilding a Honda crank you have to use a jig to hold the halfs in line

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