A new 2018 YZ250 build

Matthias_26
Edited Date/Time 6/7/2021 12:48pm
I bought a new leftover YZ250 2018 after owning my YZ250 2007 for 7 years now.

My YZ250 2007:





The new bike:





A lot of the parts from the 2007 I will be using on the new YZ250, some other parts I bought new







I'm a big fan of the HGS pipe on the YZ250



I will start with greasing everything and getting the head milled to get the squish right.

Changed the color scheme wit a black rear end and 450 front fender and cycra plate.
But the number plate doesn't fit perfect, it hits the lower tripple clamp where the OEM brake line holder is bolted on. Is this the same on a 450?








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Matthias_26 5/9/2019 11:50am
5/9/2019 11:50am
Greased the swingarm, linkage and stearing head stem bearings



Installed a wireless TMV hour meter(some tyraps for extra safety)



The Renthal twinwall 997 bars with odi lock on grips



Polished the kickstarter and brake pedal a bit, Installed the zeta oil plug and brake clevis and the hinson clutch cover.



The bud ignition cover, some grip tape on the subframe and the Moose racing dual sprocket with the DID VT2 x-ring chain




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TymeMoto
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TymeMoto 5/11/2019 3:46pm
5/11/2019 3:46pm
Grip tape on the subframe is interesting. I might have to try that. Congrats on the new bike, looks great!
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Matthias_26 5/29/2019 11:48am
5/29/2019 11:48am
Drilled 2 holes in the piston to lubricate the exhaust bridges and measured the cylinder and piston.
There is an A stamped on the cylinder but it measures 66.42mm so that's C.
Will be riding with the OEM piston for 10 hours then replace it with the right size of piston.

The OEM head is milled to set the squish and lower the compression a bit. it has 14 bar compression now with a squish of 1.5mm(OEM was 15 bar and 2.1mm squish)



Also ordered a VHM cylinder head(also squish of 1.5mm) with the 20.2cc insert to see if there are some performance differences.

Will install the Vforce3 and HGS exhaust later to compare.

Rode the bike about 30 minutes now and it sounds good. mixed gas 1/32 with motul 800




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adam8781
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adam8781 6/23/2019 9:49pm
6/23/2019 9:49pm
looks good, depending what kind of pump fuel you have access to, here in canada can get 91pump without ethanol. i run 1.2-1.3mm max squish on stock heads with timing set -1 degress from stock (.004 from tdc via dial indicator) bike runs crazy clean with tighter squish and smooth as butter -1 ignition. i think ive pushed as close as 1mm on pump but it can detonate on pump on hot deep days.

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Matthias_26 6/26/2019 9:03am
6/26/2019 9:03am
I live in Belgium, the elevation and the fuel here is is a lot different of what you have over there.
I use E5(super 98) fuel.

I think 1.5mm squish is safe for a 250 2stroke(they use 0.9mm squish on 125's), VHM will have tested this and think they know what they are doing..

The VHM head arrived but haven't got the time to test it on the dyno.





Also the decals are on the bike now!







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mxb2
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mxb2 6/26/2019 9:16am
6/26/2019 9:16am
Matthias_26 wrote:
I live in Belgium, the elevation and the fuel here is is a lot different of what you have over there. I use E5(super 98) fuel...
I live in Belgium, the elevation and the fuel here is is a lot different of what you have over there.
I use E5(super 98) fuel.

I think 1.5mm squish is safe for a 250 2stroke(they use 0.9mm squish on 125's), VHM will have tested this and think they know what they are doing..

The VHM head arrived but haven't got the time to test it on the dyno.





Also the decals are on the bike now!







Sik build
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Matthias_26 7/4/2019 9:06am
7/4/2019 9:06am
Had the bike on the dyno this week. The exact numbers are following later, don't have the prints now.
The bike made a nice linear curve with just the OEM head milled and the stock pipe on, way better than my previous bike.

The VHM head had more overrev then the OEM milled head but had a bit less torque.

The compression with the VHM head was 0.5 bar higher also.

The HGS pipe with the stock silencer made the power band wider and had more overrev then the stock pipe.
With the HGS 94db silencer the bike had a bit more torque but lost the overrev.

Also installed the kayaba fork protectors like they use on their A kit forks









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Matthias_26 7/8/2019 7:50am
7/8/2019 7:50am
D J_Tarapipi wrote:
Nice bike is the 94 db silencer the full length 1.
Thanks! The 94db silencer is the shortest one on the picture, HGS makes a standard, shorter silencer also (see picture)



The longest silencer on the picture is an enduro silencer with the same length as an OEM one

the longest silencer is not tested on the dyno but when I ride the bike it feels the same as with the OEM silencer.

I've had the shortest silencer in the past but the bike was to aggressive and I had to shift a lot so I sold that one.
alexk417
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alexk417 7/8/2019 8:04am
7/8/2019 8:04am
Where did you end up getting the plastic fork guard protectors (kit style)?
Yz229
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Yz229 7/8/2019 9:51am
7/8/2019 9:51am
Bike looks awesome! Just curious, 2007 looked clean. Why did you go with new one, just wanted to start fresh?
Matthias_26 7/8/2019 12:31pm
7/8/2019 12:31pm
Yz229 wrote:
Bike looks awesome! Just curious, 2007 looked clean. Why did you go with new one, just wanted to start fresh?
Thanks! Yes the 2007 was very well maintained but had some bad luck with a broken rod after 36 hours, then I bought a complete other engine from a 2014. complete rebuild it but then the gearbox broke after 3 hours(gears were not new but very well checked) So after that was replaced I looked around for a left over new bike.

I had the chance to buy a 2018 ant thought it was the moment for a new one after having the 2007 for 7 years.

Sold the 2007 to a friend and the bike still runs good.
cdoggy81
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cdoggy81 7/19/2019 2:57am
7/19/2019 2:57am
Nice bike & build!

I am surprised the squish was that much on both the VHM & the re-cut OEM head. If you can try cutting the OEM head to .045-.05” or ~ 1.15-1.25mm & then open the dome back up to ~ 21cc. I had really good performance at .047”- 1.2mm & 21cc.
At .05”-1.25mm with 21.5cc had more top end / overrev. .045”-1.15mm & 20.5cc & it had a wicked midrange but not as much overrev. You could also fine tune it a bit more too as you also discovered on the dyno with silencer length as I had the same results. Shorter silencers produced more tq / mid vs longer ones produced more hp/ top. You can also play with mechanically advancing or retarding the timing 1* as well 😎
Matthias_26 7/21/2019 1:53am
7/21/2019 1:53am
I won't take the risk to get the squish so tight. The fuel is different over here so are the weather conditions.

The bike runs very well now, Rode it yesterday with the long(enduro) HGS silencer, performs the same as the OEM silencer from what I can feel, sounds a bit different maybe.

Have a V-force3 that I will test later and also a heavier flywheel that was on my previous bike.

Also had the rear shock changed to the same valving as was on my other bike and a 49Nm spring that is not so progressive as the OEM spring.



MadsDausel 7/22/2019 12:39pm
7/22/2019 12:39pm Edited Date/Time 7/22/2019 12:39pm
I ran 1,05 mm squish on my ktm sx 250 17 in DK with no issues Smile
Matthias_26 8/2/2019 11:55am
8/2/2019 11:55am
I've put a reed block on the bike this week that looks very similar to the vforce3 but it's made out of aluminium and uses plastic plates instead of carbon ones on the vforce.

From what I've been told by the person who sold it to me it's a YRRD part, Rinaldi yamaha but I can't find new plates that fit on it. They are fine for now so I can test it some hours to compare it to a Vforce3.



Also got the cycra protection pads for the numberplate and the cycra disc cover installed this week.

Going to ride my bike on sunday to see how the reed block changed the bikes power.
It was running very well with the OEM reed block so I don't think I will feel it that much..



mxb2
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mxb2 8/2/2019 7:15pm
8/2/2019 7:15pm
Nice build man.
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scottb.
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scottb. 8/22/2019 1:26pm
8/22/2019 1:26pm
Matthias_26 wrote:
I've put a reed block on the bike this week that looks very similar to the vforce3 but it's made out of aluminium and uses plastic...
I've put a reed block on the bike this week that looks very similar to the vforce3 but it's made out of aluminium and uses plastic plates instead of carbon ones on the vforce.

From what I've been told by the person who sold it to me it's a YRRD part, Rinaldi yamaha but I can't find new plates that fit on it. They are fine for now so I can test it some hours to compare it to a Vforce3.



Also got the cycra protection pads for the numberplate and the cycra disc cover installed this week.

Going to ride my bike on sunday to see how the reed block changed the bikes power.
It was running very well with the OEM reed block so I don't think I will feel it that much..



is that number plate for a yzf? im looking for the same one for my 2019 yz
Matthias_26 9/7/2019 8:52am
9/7/2019 8:52am
Rode a race last week, it was almost one year ago I was behind the gate. Had 2 good starts around 5th place and finished 9th in race 1 and 8th place in race 2. Also the mechanics of Gautier Paulin and Arnaud Tonus were riding in the same class.





Bike is clean again, Going to ride a few more hours with the OEM piston and then replace it with a vertex and change the aluminium reed block to the Vforce3 because now I can't find new reed plates for the aluminium one and I don't want to wait until the bike eat this ones.




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chump6784
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chump6784 9/10/2019 2:56am
9/10/2019 2:56am
Matthias_26 wrote:
Rode a race last week, it was almost one year ago I was behind the gate. Had 2 good starts around 5th place and finished 9th...
Rode a race last week, it was almost one year ago I was behind the gate. Had 2 good starts around 5th place and finished 9th in race 1 and 8th place in race 2. Also the mechanics of Gautier Paulin and Arnaud Tonus were riding in the same class.





Bike is clean again, Going to ride a few more hours with the OEM piston and then replace it with a vertex and change the aluminium reed block to the Vforce3 because now I can't find new reed plates for the aluminium one and I don't want to wait until the bike eat this ones.




Is that the enduro silencer in this pic? I have the shorty hgs on mine at the moment and miss the over rev of my old dep setup. It does pull harder off the bottom though
Matthias_26 9/10/2019 9:11am
9/10/2019 9:11am
chump6784 wrote:
Is that the enduro silencer in this pic? I have the shorty hgs on mine at the moment and miss the over rev of my old...
Is that the enduro silencer in this pic? I have the shorty hgs on mine at the moment and miss the over rev of my old dep setup. It does pull harder off the bottom though
Yes i now use the enduro silencer. The other hgs silencer i have is 5cm shorter and had some more torque but no over rev. The enduro HGS silencer feels the same as the OEM one
Matthias_26 10/12/2019 10:44am
10/12/2019 10:44am
I ordered the GYTR steel braided lines because I couldn't fint the core moto brake lines in Europa and the shipping + taxes would cost me a lot.I had the core moto brake lines on my previous bike which I bought on 24MX but they don't sell them anymore.

The GYTR brake lines are made for the 4 stroke models but they should fit 2 stroke also.



Going to install them this winter
Matthias_26 10/13/2019 5:01am
10/13/2019 5:01am
D J_Tarapipi wrote:
Hi where did you get the enduro silencer i cant seem to find 1 anywhere
It came with my previous bike, maybe if you contact HGS they can make one, its 5cm longer than a 94db version and the same length as the OEM silencer, it performs the same as the OEM silencer also.

So if you want the same performance(more overrev) and you can't find a enduro HGS silencer you can use the OEM one..
Grovesy98
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Grovesy98 10/15/2019 12:59pm
10/15/2019 12:59pm
Awesome build and bike. I picked up a clean 2016 YZ250 a few months ago and absolutely love it. Stock engine with FMF front pipe and Pro Circuit silencer, and stock gearing. So much fun. After years on 450s the YZ has really brought the fun back into riding for me. I love the colour scheme you've gone for, and that front plate/fender/disc guard looks so cool 👌
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chump6784
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chump6784 12/7/2019 1:46am
12/7/2019 1:46am Edited Date/Time 12/7/2019 1:47am
Do you have the dyno charts yet? I'd like to see what the hgs pipe does
Matthias_26 12/7/2019 10:39am
12/7/2019 10:39am Edited Date/Time 12/7/2019 10:43am
chump6784 wrote:
Do you have the dyno charts yet? I'd like to see what the hgs pipe does
No not yet, I only have 1 photo from the first run with the milled head, Stock reeds and stock pipe

The yellow line is my previous bike(hgs pipe, vforce3 reeds, 2007) and the orange line is the first run on the new bike (2018)

As you can see, the new bike made stock already a lot better power without dips just a bit less overrev then the 2007. Now i'm running a HGS pipe and the aluminium reed block so there is more overrev now.



the GYTR brake line is also on the bike, I didn't ride it yet but the brake is a lot less spongy




Matthias_26 1/23/2020 11:03am
1/23/2020 11:03am
I bought a DEP pipe in the UK so I can compare it to the HGS pipe.

Hopefully I can test it on the dyno first. Also going to change the reed block to the Vforce3 and try the heavier flywheel because the bike is a bit too snappy out of the corners if I ride the bike a bit harder.


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