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VHM head

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Anyone on here use a VHM on their bikes? They just came out with the 2016 heads and looking at getting one for my 16 125. was gonna send my stock head/cylinder to eric gorr but hes at a 5 week turnaround time so im more interested in trying one of these VHM heads but, i cant find much info on here or anywhere really about the performance gains and if theyre worth the price tag or not. Is there a High compression insert? all i am seeing is bottom-mid or mid-top. i assume the bottom to mid would be "high comp" but im still hoping to run pump gas.. any info is appreciated.  

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Hi, we ran VHM heads on our 125s since 2012. They claim they run much cooler and certainly when you see one split away from its insert it is well made. We certainly never had any issues. We now have a couple of 16 125s and are considering what to do. You will know that these have separate inserts but KTM don't produce different volume inserts yet and I am unsure if the pre 16 sxs ones fit and awaiting response from KTM, however it's a bit swings and roundabouts as the sxs inserts are double the price of the VHM ones. I'm not sure why you would want a high compression on your 125. We have always had good results (and top end reliability) using 11.8cc inserts as opposed to the standard KTM volume of 11.6cc. Bikes make plenty of power for v fast 125 racing. All VHM inserts on the 125s use a zero deck height and 0.90mm squish so real easy to set up. We use 99 octane pump fuel at 40:1. We are going to test a 39mm carb this weekend on sand - it worked great on the pre 16 race bike but it had a heavily modded motor so we'll see. You'll be glad you've not got these XXXXXXX AER air forks yet. We have ordered cones forks from White Power which are built to your own specs and they are meant to arrive tomorrow. Hopefully. If you do go VHM loose the Allan bolt head bleeder which rounds easily and replace it with the hex bolt out of your original head.Bob.

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Well it would appear that some of the smaller European bikes -125/150 - are having issues with losing the air from the sealed chamber into the fork leg, causing the forks to drop half their travel. Unlike the Japanese air forks there is only a small spring in the right hand leg which is a last chance thing to prevent total bottoming, so the whole system depends on air pressure. Thoughts now are the lighter bikes do not run enough pressure to cause an effective seal (we run 117 psi) which is borne out by the reported lack of issues with the heavier 4 strokes which run higher pressures. KTM claim that the bike is still usable 'with total lack of air' which to be fair would get you back to the paddock but wouldn't be safe for racing. Happened to use twice at a sand track but rider noticed before luckily going over any big table tops. Our dealer is waiting on a new part from them which is being fixed under warranty. I only know 4 other people with AER forks (it's off season here as well) and small 2 strokes and they have all had problems. Presume it will all be sorted out before they land on you next year. Another issue is the new mounting system for the clamps and bars which can bend out of line and very difficult to sort out at the track. We have gone back to our phds clamps as we cannot afford things like this maybe happening at racing. However you have to use pre 16 triple clamps (we have Xtrigs). We saw it on a quick guys 350 last week after admittedly quite a big spill. Perhaps KTM should employ a few lesser standard test riders ie real world people, to really test their new kit. Bob.

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Back to VHM - I see a lot of people in the US get their 'heads cut'.  VHM offer four different volume inserts which are easy to change over and cost the price of the o rings as the deck height never changes. They also do a blank insert which can be machined to your preference. I presume this will be a similar operation to posts I see about getting the 'head cut'. This is not a big thing in the UK as we just change inserts to suit if need be, if we have a VHM head.

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Well it would appear that some of the smaller European bikes -125/150 - are having issues with losing the air from the sealed chamber into the fork leg, causing the forks to drop half their travel. Unlike the Japanese air forks there is only a small spring in the right hand leg which is a last chance thing to prevent total bottoming, so the whole system depends on air pressure. Thoughts now are the lighter bikes do not run enough pressure to cause an effective seal (we run 117 psi) which is borne out by the reported lack of issues with the heavier 4 strokes which run higher pressures. KTM claim that the bike is still usable 'with total lack of air' which to be fair would get you back to the paddock but wouldn't be safe for racing. Happened to use twice at a sand track but rider noticed before luckily going over any big table tops. Our dealer is waiting on a new part from them which is being fixed under warranty. I only know 4 other people with AER forks (it's off season here as well) and small 2 strokes and they have all had problems. Presume it will all be sorted out before they land on you next year. Another issue is the new mounting system for the clamps and bars which can bend out of line and very difficult to sort out at the track. We have gone back to our phds clamps as we cannot afford things like this maybe happening at racing. However you have to use pre 16 triple clamps (we have Xtrigs). We saw it on a quick guys 350 last week after admittedly quite a big spill. Perhaps KTM should employ a few lesser standard test riders ie real world people, to really test their new kit. Bob.

I have seen this same WP AER forks collapse in two bigger bikes(250 SX-F and 450SX-F) in ice race track also(flat track, no bumps or jumps), so there is definitely design issue. Both bikes had 1-2 hours on the clock(as they came from the factory).

Edited by needforspeed78

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