Who wants to know what is a CR 133?

[NO HAND]

I finally had a chance to test my EG 133 kit, 39mm Keihin(off a KX500) and a v-force 02model. I’ve been swapping back and forth and gone mad to jet both carbs right on the money. I can say the EG 133 kit is by far the single mod that makes the most difference. I asked for a mid top powerband and I’m really happy I did because the larger displacement does improve low and mid anyway. First big surprise was the added low end and stronger mid. The overrev is as good as it was. It is hard to notice if the overrev is stronger because I already had mid-top porting and was happy with it. One thing is clear though. It does make power unlike a regular 125. You only need to do one lap to realize it must be a cheater bike.

Now swapping carbs and reed cages. I have been switching as a set: stock carb and reed against v-force and big carb. I have no choice because the manifolds are modified and cannot interchange anymore. The 39mm carb along with the v-force was quite amazing down low. It gave me such a hit in the low-mid. It definitely feels weird to ride a Honda CR with such power down low. I found though I might have lost some over rev with that setup compared to stock. The stock setup; carb and reed cage, was very good in the upper range while loosing a bit down low. It moved the sharp hit that was down low and brought it right in the mid range. With that setup, I can say the overrev is better than before the 133 kit. What I like most with this setup is the crazy wide powerband such as I’ve never seen anywhere. It still has a strong low end for a 125 but the mid is so strong that I have been going around the track never shifting below third gear. Even in hair pins, third is strong enough to pull with some clutch work. I hate to say this but I will still have to swap back and forth to make up my mind. I’m still wondering why the 39mm and v-force give me an advantage in low-mid. I was actually expecting the opposite. I have to say that my testing session was cut short on the 39mm when I dropped the needle clip in a mud puddle. How funny. Also the throttle cable was constantly unhooking from the slide because I don’t have the plastic retainer that was supposed to be there. Then I started saying things I shouldn’t say… I ordered all I need to get the 39 going and now I’m waiting. I will do some more testing on the 39mm as soon as I get the parts. My goal is to find the overrev. Then, it would be quite unbelievable. I’ll keep you posted

Overall, I found the cage and carb are good to add a little but they mainly switch around the powerband. The 133 kit creates massive power and was so much more than I expected. If you gotta do only one thing to a bike this is it, and it’s way enough.

 

[marcusgunby]

Great write up seb-been looking forwards to it for ages.Im staggered the 39mm gives a stong low end hit-must be the jetting as i know jetting can alter a engine from a hard hitting beast to a mild woods bikes-ask any KTM 300 rider.I think if you lean the jetting in the area where the hit is it may be smoother.Also try leaning the main one size to see if you get more overev.My bike is in the dyno again tomorrow so i will report back my findings.I have bored the exhaust manifold out to 01 spec and used a cometic thin base gasket and modified the head to allow it to rev more freely.

 

[Milquetoast]

Holy bejeezus, all that stuff just makes my mind turn to lime-slushie. Thank god for 4-strokes, I have never even paid 5 minutes attention to my carb. I'm no Ricky Carmicheal either ( I'm taller), so stock power works peachy for me. :)

 

[NO HAND]

Marcus, I'm anxious to hear how the thin base gasket worked for you. Did you modify the head to keep stock compression with the thinner base gasket, or went for a different setup?

 

[whyzee]

NH, Glad you finally got that thing together, let me know your 39mm Keihin results. Is it getting warm enough to ride yet?

 

[marcusgunby]

The head is modified to this spec squish band 5mm wide,3 degrees angle,Squish gap 1.2mm and a small amount of volume removed from the dome.The head mods are done to compensate for the FMF sst which has a habit of making my bike detonate which it doesnt do with the std exhaust.I have rode it already and it seemed to work as i wanted-a tad more bottom and with the bored out exhaust manifold it overevved ok.I only got to ride for 15minutes in practice as racing was called of due to DUST!!!

 

[NO HAND]

I just wanted to post online the jetting specs once adjusted for the EG 133 cylinder. Asuming everything else is stock, I ended up with:

Mikuni36TMX
Main: 400
Needle: 3rd clip
Low Speed: 50
Air Screw: 2.5 turns out

This is definitely different than before the EG 133 mod. I was using a 370 main, with a 35 low speed at 2 turns out.

Keihin39PWK
Main: 210
Needle: 1st clip (and still too rich)
Low speed: 52
Air Screw: 1.5 turns out

 

[marcusgunby]

Seb those cahnges to the jetting are major im surprised it altered that much.Did you end up doing the powervalve mod where you match them to the top of the ehaust port?

 

[NO HAND]

Yeah eh? It's quite crazy the difference in jetting. I don't know what to think. The only thing that wasn't stock was that I put on a 01CR250 rubber airboot. It would have been such a pain to un-glue it again and test both airboot back to back. I can't tell if it's a step backwards or not. :eek: But what the heck. It was fun putting it on :confused: . To be honest, when I was comparing both airbooth in my hands, I had to look at them for like 10 minutes before I could notice a small difference in shape. I guess that is such a small difference that it has no effect on jetting. Oh, the other thing that isn't stock is the powervalve spacer. I measure to have 15mm of p.v. hanging out in the closed position(measured in the longest point). That forced me to use a 9mm pv spacer. I didn't do yet the Boyesen style PV mod. I was thinking about it and I plan to try it. I have to prepare myself psychologically to grind off that much material off my pv. Was it hard to do? I don't have much info on it. I just have a picture. Do you know someone who would have drawings or more precise specs? I would definitely give it a try.

 

[marcusgunby]

Seb i worked from the drawing-if you look up the exhaust port you can see how the std set up hangs down into the port-not good.As you grind back the valves-(print the picture out as large as possible with decent quality)you will see that the shape has to be as it is in the picture-if you remove some material from the powervalves and refit them you will see why they are shaped that way.Its not at all hard but does take time as they are hard buggers.Mine took about 1.5 hours all in.

 

[e.c.bert]

Hey Marcus, is the power-valve mod the real thin look I recall from a photo here at DRN? If I remember correctly was the valve cut down so much where it could break? I am wanting to do a 144cc EG Rocket so some feedback would be appreciated on this post.

 

[marcusgunby]

Yes its the one pictured in Rich Rs photos -i have dome mine and so far so good.

 

[whyz]

just one ??

Do you have to adjust the timing at all,, When going to the big bore?

Thanks....

 

[NO HAND]

You don't need to fiddle with the timing when you go for a big bore kit. You need to re-adjust the jetting though. First race of the season and I get the holeshot. That's not like me because I never had it last year - even though I was trying hard. I just wanted to give you an update of how it goes on the track. This was the race season opener. We only did one heat because of the the sleet falling and the poor visibility. It is so much easier to get the holeshot with the 133. You can be sloppy and shift early and it pulls it. There was so much mud and snow on the track that I was scared of the loose berm in a high-speed corner where the wheels blowed through in cornering and some riders passed me there. I finished 4th and that was a happy day for me.