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Phat Head Racing heads

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Just curious if anyone has any experience with the Phat Head Racing heads for the KX250 ?

I have a fresh 2007 KX250R and was wondering if these heads are all bling or if there is any measurable performance to be had ?

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I have them on both big bikes, had one on my sons 100/112. There is absolutely no bling about them. They are all performance. Bigger water jackets, removable/tunable domes, etc. Oh, nad they add some bling to the bike. LOL

I've used them on bikes for years and never had an issue..ever. They are great people to work with too. You get your chioce of 2 domes. botht he same or 2 different sizes. I got stock and 1 under stock for each bike. Both will still run pump gas but I run 70/30 pump/VP110 with the 1 under stock. HUGE improvement even with reg pump 93.

Just don't forget the o-ring on the dome where the sparkplug boss is. I did that the first time years ago. Bad water leak... :bonk:

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Edited by SAPPERS

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Good to know , thanks . Just looking for ways to make my engine a bit more fuel tolerant . The best pump fuel in my area is Shell V Power and detonation is an ongoing issue . My bike is just for trail use , but , I want it to work as good as possible . I've see first hand what detonation does and I don't want to go there . VP race fuel is available , but it is extremely expensive . Not feasible for trail use . I'll look a bit harder at the Phat Head option .

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I know VP is expensive but if you're having a detonation issue, all you need is 1/2 or 1 gal to a 5 gal. mix. That should help you alot. That way, a 5 gal can will last you 5, 5 gal cans of mix and possibly save your motor.

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At $130 per 5 gallon can ,VP race fuel is just too expensive . In the long run , I would be better off finding another solution . This bike is new to me and I've not had an opportunity to really ride it yet . I've only had it out once . The previous owner said that it had a detonation issue with pump fuel . At first look , I was not happy with his "tune up" so I have made changes . In the next few weeks , as the weather gets better and I will try it out to see for myself . If there is an issue as he claims , I will try to tune around it . Failing that , I will consider other solutions .

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$130/5gal.. WOOOOWWWW!!!

Someone's getting rich. Down here I get it for $6.50/gal. Either I buy a 55gal drum and sell it or a friend will get a drum and I buy it from him. We sell for $7.50/gal.

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Race fuel is NOT cheap around my area . The local drag racers buy it by the 55 gallon drum and it is a big investment !!! Simply not practical for an off road bike .

I'm pretty confident that with proper tuning , the engine will be just great . The one and only time that I rode the bike , there was no detonation , but , the previous owner had lowered the clip on the needle to prevent detonation and it was running WAY too rich . Plug was just dripping in fuel .

I'll have it screaming in no time :bonk:

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Sappers,

Did you put the Phathead on a KX250 or only the KX125? I have an 05 KX250 that I'm considering putting it on instead of modifying the squish on the stock head. When you mentioned huge improvements, what was improved ... more power, no detonation, improved throttle response? ... Thanks, Joe.

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As part of figuring out how the previous owner of my 2007 250 had my bike tuned , I just checked the air gap on the crank sensor . I was set at just over .070 .

Good grief . I wonder what effect this would have had on engine performance ?

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Yes , but I don't want to run retarded timing to reduce detonation . I'd rather fix it the right way and run full power timing . Things work so muh better that way .

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Sappers,

Did you put the Phathead on a KX250 or only the KX125? I have an 05 KX250 that I'm considering putting it on instead of modifying the squish on the stock head. When you mentioned huge improvements, what was improved ... more power, no detonation, improved throttle response? ... Thanks, Joe.

Both. The pics are of the 125 & 250. Both just have blue. But yes, it helped all the way around. Motor ran cooler. I can't say anything about detonation because of the fuel I run and I always jet spot-on or eal close. But with one size smaller domes in each, bottom end power was instant. My son said the 250 lost a little on top near over-rev but he was shifting by that time and allowed the power in the next gear to propel him. He only weighs 125lbs.

I did have to fab new top motor mounts. For some reason, they didn't fit just right so I just made my own from aluminum stock.

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Hey guys just joined TT finally and i have a 2003 kx250 2 smoke(love the bike) all it has is full pro circuit exhaust so far. Been riding for about 8years trails and some MX tracks, i live in MA, im looking to get the bike ported and polished and have really been looking into phat head racing heads, now r they worth the $180 if i get the port n polish? Running race gas isnt really an issue if i do or dont have to run it, was told to run VP c-4 with 93 50/50 mix. Also who do you guys suggest for the port n polish job, anyone local in New england or MA that r good at it? I know eric gorr/millennium technologies is good along with pro circuit but they r semi pricey. Any opinions and suggestions will be greatly appreciated

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I have them on both big bikes, had one on my sons 100/112. There is absolutely no bling about them. They are all performance. Bigger water jackets, removable/tunable domes, etc. Oh, nad they add some bling to the bike. LOL

I've used them on bikes for years and never had an issue..ever. They are great people to work with too. You get your chioce of 2 domes. botht he same or 2 different sizes. I got stock and 1 under stock for each bike. Both will still run pump gas but I run 70/30 pump/VP110 with the 1 under stock. HUGE improvement even with reg pump 93.

Just don't forget the o-ring on the dome where the sparkplug boss is. I did that the first time years ago. Bad water leak... :banghead:

IMG_0061.jpg

IMG_0062.jpg

Your info is outdated. Phathead is now owned by lukes racing and you dont have a choice of domes unfortunately.

Now i have one and love it but i do only ride trails and its more of a top end upgrade. Im no exactly sure what detonation sounds like but i run non-ethanol 93 and im confident it got rid of any detonation issues because of its squish band width.

The only thing im disappointed about is i wanted a blue one but the guy i talked to said he had only black and aluminum for my 06 250. So i got black. Well, the damn thing is half purple..... It seems like lukes is just trying to sell whats left of phathead stock and trying to be done with it.

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Yeah i.know its.owned by lukes racing now and his prices for a port n polish was $100 and $50 for powervalve now thats a great price buttt ppl say u get what u pay for so im wondering if its quality work and he suggested the phat head racing heads which r $180 so basically $230 for the package but r.the phat heads worth it? I ride trails almost all the time so will the head benefit me in trails? Thanks

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