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Next round of general 660 mods

8K views 45 replies 8 participants last post by  oldskool83 
#1 ·
IMS heel guards to work with my roll design pegs. I ran over a foot alone time ago since it walked off stock pegs, if I can find good parts I buy them strengthen which these were not welded the best. Now they are out for blsck powder coating.

Welded up a broken tie down for toe strap to keep up front with my machette for trail cutting.

Next going with stage 1 got cam and new chain. A kid owes me money yet so that's free parts to me somewhat.

Followed by +4 to +5 swinger.

Hope to drop in higher comp piston and call it a few years.

Stay tuned.
 

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#2 ·
LED Headlights for the water tunnels going under the highway in coal country. Talked to my guy at KB5 on motor. He wants to either use my cam for regrind or billet cam. The cam builder is gonna run my hp numbers so that will tell me which way we go. .25hp does not lead me to spend $100 more.

Next he wants to mill head to compensate for the bottom end loss I could see. Prob not much of a mill. We did this in my banshee which helped, did it in my civic too after I warped a head.

Lastly a good port job.

All of the teams race bikes are done this way. In theory it makes sense of you want a bottom end to stay stock and get long life out. Have to see what valce train looks likeince we go into it soon.

I was told after these three last mods I should have all I need to do the job. Im a woods guy who throws in hills, which there was not one yet I have not made up.
 

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#3 ·
Milling the head on a 2 stroke will increase compression without problems. Milling the head on a 4 stroke will affect the timing chain length and make it loose, as well as retard the timing. If you need compression do it with a higher compression piston, then machine the head, cylinder and piston if needed for desired deck height and final compression.
 
#4 ·
Never heard of that after being in the game 27 years. Milled head will allow piston to come higher only. I'm going to focus power more mid if we can. 10:1 compression I want more torque, if I don't do hills I don't need much added to top.
 
#6 ·
A 2 stroke has no cam so milling any component will increase compression without problems if done correctly.

Milling the head will not allow the piston to come higher, milling the cylinder will. Milling the cylinder will decrease deck height.

Milling a 4 stroke head or cylinder "will" increase the compression and move the cam closer to the crank, that will make the cam chain looser. A loose cam chain appears to be worn to the motor, changing cam timing and the adjuster be extended unnecessarily, reducing operation when the chain or gears wear.

You want torque, add a 4mm stroker, You want torque and HP, increase compression.

Experience, I've worked, modified, machined, ported and been building motors since the early '70s. Yeah, I know, that makes me older them most of you.
 
#7 ·
Not opening a motor that has 2years run time in it. Bike sat in new condition 14 years...nothing inside is tired now will a 10:1 piston kill a stock rod. The name of this game is not to go haam on a trail bike that's not tired, if I had a blown up one then yes I'd go haam inside also. A cam and a tiny compression bump with porting, then go ride it another season see how it works for the trails.
 
#8 ·
I wouldn't consider putting a high compression piston on a stock rod regardless if it's "tired" or not.

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#10 · (Edited)
So I've read. I am going back to talk about other options vs keeping it a hair above stock.

two options then I am willing to do.

(1) Leave the motor stock, throw in a mild cam (either his custom profile which is a megacycle or hotcam 1) do porting
while it's off and call it a day until it smokes.

I could then progress to the next level

(2) Rods (vesrah, hotrods, prox)
bumping compression and same mods as above.
 
#11 ·
A 4mm stroker has been a popular upgrade.
 
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#12 ·
He throw out doing a custom +2 crank they could have made for me. One was done for another guy that did a pretty powerfull but yet very realiable 660. I kinda only wanna do this once but at same time I want to feel I got somthing of spending $500-$2000. He didn't seem keen on +4 with stock carbs just trail riding at mid throttle max. We are going to talk more estimated prices and lead times. This would not be 1st motor has gone in for me.

I had a kx112 built one is a atc2500x
And he fixed my yz265 in which Eric goor milled off my cyclinder when I didn't ask for it...that bike pinged on c12.

I hope to start buying parts in a few weeks.
 
#14 ·
A +4 crank will give you the bottom you're after without milling the head and also getting around the 660s weak rod. Your head will be much more of a determining factor on carb size than a stroker crank. Since you are using the bike for trails, ide assume that's lower speed and not much high rev time. You'll be fine on stock carbs.
 
#15 ·
Id do a 4 mill. Weather its a top end motor or a bottom end tractor is going to depend more on the porting, and the camshaft used.

Yes a 4mill will gain you a lot more bottom end grunt. You don't have to keep it. You can give it away in the form of running a more aggressive cam shaft that will build more power in the top end, and still have a decent bottom end when compared to the same build on a stock stroke crank.


Also I wouldn't ever mill a head on a 4 stroke to gain compression when you can simply swap out to a higher compression piston. No need in screwing up a head that cant be reversed once done instead of swapping out a piston.
 
#16 ·
Part of me wants to just drop in a stage 1 cam, run it...$175 drop in the bucket. I'm not trying to fix what is not broke, I have other toys also. A kid owes me about $500 yet so seeing what options are as far a buying parts. I know a stage 1 cam is not gonna kill a stock rod. bike should run flawlessly for years.

Can you even just buy a +4 rod to blow on my oem crank after a true and rebalance?

The I'd do this and that is one thing, on a bike that had not even 50hrs before I got it is the other thing....I'd kinda like to let as much together as I can.

I am on board with not milling head, he weanted to do 10thousands max off. I do not seem keen on it the more I think about it. I'd rathmoney to open up bottom end at that point. $135 for a new rod is not a big deal.

If I go rod is go compression, if not im more inclinded to blow in a cam and go about my day another year, see if I still want the bike. Ive been known toget a different bike or two a year for the last 5 years. That's another reason im iffy to go balls deep.
 
#17 ·
Can you even just buy a +4 rod to blow on my oem crank after a true and rebalance?
The crank webs are different on a stroker crank. The pin that the big end of the rod rides on is moved farther out from the center line of the crank by +2mm. This causes the piston to travel 2mm farther down in to the cylinder, and come up out of the cylinder 2mm for a total length of +4mm. The hot rods crank uses a stroker piston that has the wrist pin moved up to keep the piston from popping out of the cylinder.

Moving the attachment point of the rod out from the center line of the crank gives the rod more leverage when turning the crank. Its like using a longer wrench or a cheater when you have a tight bolt.
 
#19 ·
I looked into 700s. As cheap and be a 06/07s are I spend more in handling parts and exhausts. If I'd go 2010+ im at 4000+. I'd have to hope to sell my 660, it was clean and mint, it's bashed up coal country bike now. I've chosen to do this after not thinking on it much as my next bike I want a 4x4, not as only bike however.


Stage 1 cam and new cam chain if in sides look heathy. Port and clean up head while I am in there. Go about my day for 2018 on this mod.

Mid 2018 buy a rod and increased compression, maybe 10:1-11:1.

Open back up refresh, if I feel I need more speed at that time drop in stage 2 spring's and new valves. By this time I'm a solid 35year old and can decide if sport is still up my ally.

I'm rebuilding a kfx700 right now again so that may become,my main bike again unless my tecate does.

That's the problem when you were a but sell trade for awhile and aquired some cool nice things for trades.

As of now I think I'm happy to spend $500 and make it a very mild build , basicly all bolt ons. I will report on progress by end of week.
 
#24 ·
I only have one last question that I didn't ask anyone.

If I blow in a stage 2 cam with springs would I feel anything other then some extra rev? I want to know if it would work on stock compression for a year til I decide if I wanna go into bottom end. Let me know please. I've started a spread sheet of different options with prices on what I could buy.
 
#25 ·
There is a ton of info on this on this site. If you just put stage 2 cam in a search you'll get lot's of hits. I've done it to learn about the cam in my quad. From what I've read you'll get some additional power from the cam but you really need a higher compression piston to see the most benefit. Most say you don't see much low end but more mid and high revs. Other more experienced can probably give you a better idea.

You should really save up and get the cam and piston so you can do them both at the same time to get the most out of it.
 
#28 ·
Thanks, that's what I was looking for. I'll just have my buddy buy me a peice a week, I'll save it then on a cold day have it all done. Money is not the issue, just so much other crap I wanna do I'll just pick up deals when I see them. I guess if I have a real nice increase I do not need to use it all in certain riding spots.
 
#29 ·
Can I reuse washers and retainers from my head? I ask since I found a stage 2 with chain and just springs. Let me know. I didn't see anything in hotcams site like that or saying I could or couldn't
 
#31 ·
#33 ·
I bought a Stage 2 after digging thru 100 some posts on stage 1. Next week or so I'll pick up the spring kit. I'm parting my tecate to fund these mods. Rather have one powerfull bike that does it all rather then 3-4 toys.
 
#34 ·
Got burned on stage 2 deal no money loss. It was bad, bought a new stage 1 and cam chain. Next is open head will get ported at KB5 prob next month.

Roll design heel guards back fro. Welding and Powder coating. They feel good, see how they work this sunday. Should help when playing on the loose steep hills...that little guy is me in my wife's 700 turning it around.
 

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#36 ·
Swinger is off, going in gig Monday for + 4.5" tubeular style. My end goal is at least a 53" wheel base. Somthing close to stock quadzilla. With the eccentric career I have 1" of adjustment. Hope this is the b allance of climbing and trail riding, so far plus2 has made this bime feel like a stock length 450r with no issues in right stuff.
 
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