OTR Cylinder head + Racing Camshaft vs. Reliability - .: XT660.com

ArtVark · # 1 25-05-11, 23:53

Hi all!

I've been looking at getting a bit more power out of my 2006 XT660R. I already have DNA and K&N filters, a PC III and an OTR 2-1 Titanium exhaust. I am interested in the OTR racing camshaft and cylinder head modification:

http://www.off-the-road.de/XT-660/XT...ft-XT-660.html

http://www.off-the-road.de/XT-660/XT...-standart.html

I read a post that reported a positive result from the camshaft. The cylinder head mod is supposed to give more power as well, but I am also interested in it because 'the thermal behavior of the engine will change in a positive way'. Having been stuck in traffic jams in the Middle East, there are many times I wished for better 'thermal behavior' (i.e. not having to stand with my legs wide apart to avoid my skin melting...). I know a large amount of my heat issue is because of the OTR 2-1 exhaust running right by my leg and have a small heat shield on it that helps a bit, but any cooler is always good...

Does anybody have experience with the OTR cylinder head mod? And any advice on how a racing camshaft and the cylinder head mod may affect reliability? Apart from having some fun around Holland I also use my XT for long road trips, and so far the engine has been faultless no matter what crappy gasoline I fed it. I understand that any mod is always a bit of extra risk, which is acceptable, but I don't want to end up in the middle of nowhere with an exploded engine just because I could get there faster...

Also, any recommendations for similar parts from other manufacturers? Or perhaps I am looking at the wrong thing all together, and other mods would be more cost effective/reliable?

Greetz from Amsterdam! :-)

Kev · # 2 26-05-11, 02:03

If you fit the OTR cam & ported head to a standard XT660 bore you would loose quite a bit of bottom end & mid range torque & HP, yes there is a good gain at 6500RPM. You would need to up the compression ratio & bigger bore to get back the bottom & mid range HP & Torque with the OTR parts

I did 10000kms on my Raptor 700 cylinder big bore with ported head & stage 1 hot cam with no problems, I would only use a CP piston because of it's longer piston skirt compared to JE & Wisco pistons.

Out of the 7 big bore kits & head jobs with cams that I know of, only one bike had a problem with the plating coming off the bore, due to poor plating.

ArtVark · # 3 26-05-11, 15:12

Kev to the rescue :-)
Thx for the heads up on the low and mid power dropping, that's exactly what I don't want. Is this the result of the head, the cam or both? Going the whole hog with bigger bore and the extra compression is way over my head...
The cam by itself seems good value for money, after I posted yesterday I saw the post by tarzan on his heat wrapping solution which seems good for my heat issues. So if the cam by itself provides some extra power without too much drop in the low and mid range that would be great.

As a true cheap Dutchman, I have found the very best bang for buck mod. It's a bit loud and the gas mileage sucks, I may also have some new heat issues. On the other hand, there is no extra stress on any parts of the engine at all, and if it dies you can still keep on going:
http://cgi.ebay.com/ebaymotors/jet-e...a10e37391#shId

hazza2805 · # 4 27-05-11, 15:01

hahaha

Fiddich · # 5 27-05-11, 17:16

Bet Kevs been there done that!

Aye and guaranteed to lose your bottom end when it decides to go pop.

Kev · # 6 27-05-11, 21:57

Nice I want one.

Want your XT to go better fit a stage 3 air box a set of cans with a power commander, more HP & torque everywhere.

When you port the head & fit bigger valves you will loose port air speed low down & will have reduced torque & HP, that's why you need to up the compression ratio to get it back.

A high lift cam has the same effect by taking from the bottom & mid range & moving the power up the rev range. Add a high compression piston to get the bottom & mid range power back.

ArtVark · # 7 30-05-11, 23:10

Thanks Kev. All this is way over my head. I have all the 'easy' mods like filters etc, and thought I'd try something a bit more daring. But seeing as I would now need a whole load of mods it would be too much for me.
I have been reading on the forum about upping the compression. I don't understand the principles involved to be honest, but it looks like as the compression ratio gets higher the engine becomes fussier about fuel. And that could cause problems when I'm riding in countries where the fuel has lower than normal octane levels.

You recommended the Stage 3 mod. I had not really thought about it yet, as I am running with K&N and DNA filters already. But comparing numbers, I see could gain as much as 4+ HP by upgrading. And it is a mod I should be able to do myself (was planning to let the garage do the cam mods etc.).
And as there's more air, perhaps a nice combo would be more fuel as well in the form of a +2mm (or maybe even +3, which I saw floating around?)throttle body? I think with the stage 3 and throttle body I should be able to get a nice little final power boost without digging into the internal workings of the engine too much.

I found the threads about the +2mm throttle body conversion from KDS Racing, but KDS Racing does not appear to be around any more. Can anybody recommend an other source for this? I know OTR can do it, but it looks expensive compared to what KDS Racing apparently charged.

I could also look at some other cans, but I think the OTR 2in1 I have is pretty good already, and I have a PCIII as well. Will need a new Dyno run if I do the stage 3 and +2TB, but I don't quite trust my current map anyway...

Thanks for all the advice so far!

edit: And perhaps get a Nology High Power Ignition Cable as well, looks easy enough to do even for me :-)

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