Going up 2 teeth? (not a MXA joke) aka Finding bottom in Hondas 250f

Related:
Create New Tag

4/9/2021 6:15 AM

So the new Honda 250f leaves a lot to be desired on the bottom end.

I'd like to avoid the high compression piston + race gas approach because of day-to-day cost and reliability.

I've gone up a tooth, would going up two help?

What have folks found to be successful?

|

4/9/2021 6:18 AM

mtl wrote:

So the new Honda 250f leaves a lot to be desired on the bottom end.

I'd like to avoid the high compression piston + race gas ...more

I put a GET ecu on mine, it really changed the entire bike, Vortex would as well. Went to a 49 and it would carry 3rd much better, and "recover" way quicker.

Beware, you'll need to keep your battery on a charger as they do wear the battery quicker.

|



youtube.com/iridea250fyamaha

4/9/2021 6:24 AM

Love the thread subject line!!!!

|

GP740
Since 1987

4/9/2021 6:47 AM

2019 CRF250R 13/50 Don't ever run anything else...

|

4/9/2021 9:55 AM

Get the ECU and make minor gear ratio changes. You stray too far and it will start to suck. God is that engine lacking in the bottom end its not even funny

|

Gone:
2006 CRF230F
2008 KTM 200 XC
2017 KTM 250 SX
2019 CRF250R
Current: 2021 YZ250F

4/9/2021 11:12 AM

+1 for the ECU. I have to say I don't quite get the over-dramatic claims that the 2020 has no bottom (can't attest to the 18 or 19 as I've never rode them) but while it may be geared more towards mid-range and top-end power it still has plenty IMO. I did fancy a little more power in my 2020 (who wouldn't) and picked up a Vortex and have to say it made a massive difference across the rev range. Haven't played with gearing yet as I like the stock gearing but would definitely recommend the ECU.

|

4/9/2021 11:47 AM

Great feedback, thank you!

I'm coming off of 2018 unicam gen bikes (still have one as a backup bike) and the bottom is a night and day difference.

Anyone know what 2022 holds for these, totally new bike or continuation of the current frame/engine?

Also, is there a known good map that someone could share with me if I were to go the ECU route?


|

4/9/2021 12:05 PM

NOTICE: Changing gear ratios does not "give more power".

|

The above may be fact or fiction, I may be serious, I may be jesting. I am not sure, you have no chance.

4/9/2021 12:11 PM

Correct, adding teeth to the rear just makes the bike rev up faster. A bandaid fix. I went to a 49 on my 19, bike stood up in corners and made 3rd incredibly short but the bike doesnt have the low end torque to pull 3rd through tighter inside ruts

|

Gone:
2006 CRF230F
2008 KTM 200 XC
2017 KTM 250 SX
2019 CRF250R
Current: 2021 YZ250F

4/9/2021 12:30 PM

Right now our team is typically racing with a 49 rear, occasionally a 50.

Full engines of course...

Best recommendations for budget/non race engine build...custom Vortex ECU from XPR...Rekluse torq drive manual clutch.

The pirelli’s we run are fairly light too, which helps.

Big recommendation, do not lighten the flywheel. I’ve seen a few guy go this route. It feels more lively in second gear and even third, but it blows through the power too quickly when it gets into it. It’s not as ride-able per se.

|

4/9/2021 1:11 PM

Tokyo mods reflashed my ECU. Also went up one tooth on the rear and full Yoshimura exhaust. Best advice i can give is to rev the bike. The engine is reliable and was built to run in the higher RPMs. I have 106 hours on one of my engines and valves, bottom end are still in spec. Piston changed every 30 hours.

|

4/9/2021 1:14 PM

ML512 wrote:

Right now our team is typically racing with a 49 rear, occasionally a 50.

Full engines of course...

Best recommendations ...more

Would this change for motocross?

Keefer says: I went back and forth between the stock 13/48 gearing and 13/49, but ultimately decided on sticking with stock. Why? I felt the 13/49 gearing made second gear less usable and didn't help me get into third gear any quicker. The 13/49 robs too much top end away from second and third gears on medium to faster flowy tracks. If you’re riding a tight track and suffer from bad corner technique going to a 13/49 could benefit you more. Decide which tracks you ride the most and what type of rider you are in order to decide which way to go with your gearing.

|

4/9/2021 1:59 PM

spacecat wrote:

Tokyo mods reflashed my ECU. Also went up one tooth on the rear and full Yoshimura exhaust. Best advice i can give is to rev ...more

How does it feel with this combo?
Is it just one of the 3 stock maps that get altered?
Can you pick which one if so? Can you still switch between maps?

|

4/9/2021 3:37 PM

RedRider785 wrote:

How does it feel with this combo?
Is it just one of the 3 stock maps that get altered?
Can you pick which one if so? Can you ...more

The flash only altered map 3. You can still use the other maps with the stock handlebar switch. It made a noticeable difference but its still no yzf on the bottom

|

4/9/2021 6:36 PM

spacecat wrote:

Tokyo mods reflashed my ECU. Also went up one tooth on the rear and full Yoshimura exhaust. Best advice i can give is to rev ...more

RedRider785 wrote:

How does it feel with this combo?
Is it just one of the 3 stock maps that get altered?
Can you pick which one if so? Can you ...more

I have both for my 20 .Tokyo reflashed and a vortex mapped by twisted development. Without a doubt the mapped vortex was a huge upgrade over stock and even a big noticeable difference over the Tokyo /stock ecu. I run the vortex, full yoshimura, rekluse torque drive clutch and 49 tooth rear sprocket. It’s a lot of money in upgrades but I will say this is the best bike I’ve ever owned. I’ve owned a 2015,2016,and 2019 yz250f. The low end isn’t the same as the yzs but it’s not that far off. I just wish the Honda came the way mine is now.

|

4/12/2021 9:04 AM

Wolfey wrote:

I have both for my 20 .Tokyo reflashed and a vortex mapped by twisted development. Without a doubt the mapped vortex was a ...more

I understand the mods except the Rekluse. What is it giving you in terms of power (or power delivery) that the traditional clutch isn't?

|

4/12/2021 7:07 PM

The rekluse has less slip than the oem setup.It improves low end drive.

|

4/15/2021 11:37 AM

2020 has Yosh exhaust, XPR vortex, recluse torque drive clutch, stock gearing and back fire screen removed made a pretty significant difference. Picks up much sooner on the bottom and revs out hard to the increased 14,600 limiter, can use 3rd in most turns except for tight 180's. Too bad they don't come this way stock. I rode a 18 and it was gutless on the bottom.

|