Just fitted Hotcams + having problems - Help please!

Hi :thumbsup:

I am hoping for a bit of help!

I bought a pair of Hotcams for my 2004 WR450 (4023-1IN + 4044-1E) and installed them this evening. Unfortunately I couldn't get the bike to start, There seems to be too much compression, the electric start would only crank it over for a split second then die and the kick start is*stiffer than normal*and the bike 'kicked back' and backfired twice. I only tried it a couple of times and thought best to remove the valve cover and check everything again.


It all looks good, i was extremely careful and even marked the timing chain and the original Yamaha cams with tip-ex. The TDC mark is lined up with the cams pointing outwards and the cam marks lined up with the cylinder head.


On my bike there are 3 TDC marks on the stator, after searching here people say to use the 3rd mark (which lined up perfectly with the Yamaha cams). Is this correct one to use with the Hotcams?

I also noticed on the hot cams exhaust cam the second dimple/timing mark is in a slightly different place to the original Yamaha cam, it has an 8 tooth gap where the Yamaha has only a 7 tooth gap.

Is this correct, as it does not face 12 O'clock, it's slightly further round when installed?

My valve clearances were very slightly too tight for the Hotcams spec, (with the stock cams it ran perfect)*I will re shim these tomorrow but unfortunately I don't think this is my problem, could you give me any pointers?

Many thanks!


Sounds like cam timing... take it apart and try it again.

I can only speak from my experience with YZF cams but I did have what you are describing happen... just took it apart and did it again... I hate timing these motors:banghead:

Thanks for the reply :thumbsup:

Do you think I should I try to time the engine using the 1st TDC mark then?


Thanks for the reply :thumbsup:

Do you think I should I try to time the engine using the 1st TDC mark then?


No, I would use the 3rd mark... does everything look spot on after you get the chain tensioner installed? If you have slack between the cams or between the ex cam and the flywheel when you install the tensioner it can screw things up enough to do what your experiencing...

I could not locate the thread but I did copy and paste this onto a word doc. and stuck it in my manual. It is quoted from post by Grayracer over in the YZF forum -

The next thing that must be looked at in timing cams is that the crank can turn nearly 10 degrees without moving a cam if the tensioner is off the engine. When you think you have the engine timed, rotate the crank backward until it starts to move the intake cam, then manually rotate the exhaust cam back until it draws the chain tight, and then do the same to the intake. After that, rotate the crank forward until it arrives at TDC again. This will pull both cams into the actual position they would be in were the engine running, with the front and top runs of chain drawn tight. See what the marks look like in that position. Not doing this screws a lot of guys up.

Good luck:ride:

Many thanks SJMC_DON, i will try that.......

Can anyone clarify that you 'time' the hotcams the same as the standard cams? That means to me:

Crank alignment mark on the 3rd mark (not the H), cam dots aligned with the cylinder head and the cams facing outwards, ooh and put something down the plug hole just to make sure your bang on TDC - Am I missing anything?

I swapped over one cam at a time as to not mess the chain etc up. I did turn the engine over many times by hand before installing the cam cover and the chain looked fine, no slack etc.

I ended up putting the standard cams back in, (fitted exactly as they came out and the hotcams went in) and she fired right up with a 2 second stab of the button and runs sweet like before.

I am confused now - I thought i had the timing correct but it would not start with the hotcams installed, maybe a decomp problem?......................

Thanks :thumbsup::worthy::busted::blah:


Hopefully you can get them working, i've read about a lot of problems with the hot cams regarding starting with the e button, not sure if this has been sorted or not.Keep us posted

Right, i installed the intake cam with my standard exhaust cam and she fired right up with a stab of the button as usual!! :worthy:

I had an e-mail back from Hotcams, they said if I send the exhaust cam back they will change check it over and change the decomp pin etc if needed :thumbsup:

Thanks everyone!


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