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  • NORMAL+α If you want it, this is the one.... (YOSHIMURA: ST-1M Camshaft)
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【YOSHIMURA】ST-1M Camshaft Review
ST-1M Camshaft YOSHIMURA
YOSHIMURA
ST-1M Camshaft

Fits: YAMAHA SR500, YAMAHA SR400

Japanese Webike user
5/5

NORMAL+α If you want it, this is the one.

This time, when the store did the Overhaul on the SR400 above the waist. "Would you like to change your Cam with Refreshed Engine?" I was invited to change it (laughs).
I thought it would be safer to use the one that has a lot of data and many examples of installation, so I installed “YOSHIMURAST-1MHigh Camshaft” on SR400 this time.

I was invited to buy the same YOSHIMURA STAGE-2, or ST-2, in stock at the store and offered a discount, but........................bad bugs!

However, this is a NORMAL400 with only Tune for the intake and exhaust, and I don't want it to be too radical and difficult to ride (laughs).

Types of YOSHIMURACam for SR
■ STAGE-1 (ST-1, ST-1M)
STAGE-1 (ST-1, ST-1M) STAGE-1 if it is used for Sports driving, etc. 。 Power is generated mainly at low to medium RPM, so it can run more briskly than the NORMAL Camshaft. 。 STAGE-1 is the best choice for those who often drive a lot of Gymkhanaetc.STOP & GO. ST-1Camshaft for SR500/400 is no longer available, and the re-released version is ST-1M.

■ STAGE-2 (ST-2)
STAGE-2 (ST-2) STAGE-2 for those who place emphasis on high-rpm driving in the Race. 。 STAGE-2 is set to generate power at high RPM range, so it can be said that the specifications are higher than STAGE-1. To prevent Valve Surging etc., it is necessary to change to Valve Spring specified by YOSHIMURA. 。 However, the power at low rpm may be sacrificed due to the high rpm power output, making it a very difficult motorcycle to use for those who use STOP & GO frequently.

In other words...
STAGE-1 (ST-1, ST-1M)
→Valve Spring does not need to be replaced, Torque is relatively easy to ride out from below.

STAGE-2 (ST-2)
→Valve Spring needs to be replaced, Power comes out when turned, but Torque is thin underneath.

Based on my running style and EngineSpec. STAGE-1 (ST-1, ST-1M) I've got it!

I asked for it at the restaurant, but the procedure was.
Procedure
◎First, lower the Engine. It is better to take it down because there are many small parts.
↓
◎Remove the cylinder head.
↓
◎Match the notch on the Crankcase with the top dead center Mark (T) of the Flywheel, the 0Mark of the Camshaft Sprocket with the notch on the Cylinder head.
↓
◎Remove the locker arm, remove the camshaft, and then use the ValveSpring compressor to remove and replace the valve spring and stem seal. 。 After installation, use the Thickness Gauge and Tappet Adjust Wrench to return the Tappet clearance to the proper setting.
*Locker Arm must be replaced for 1985 and newer vehicles. Locker Arm
(YamahaOEM Product No. 583-12151-00) ×Quantity:2pc. Set
↓
◎The assembly process is the reverse of the removal process. Finally, the amount of oil is checked and replenished before starting.

[After exchange]
◎Blow up is sharper than NORMAL. → No drastic change, NORMAL+α.
◎The Torque loss at low to medium speeds, which was a concern, is not felt.
◎Firmly follows the accelerator operation even at high speeds 。
◎Idling is stable, and the Accelerator operates as usual when starting, with Large sturdiness.

I'd like to thank you.
SR400 is originally a short stroke model, so I think you could feel the lightness of the short stroke by using the high camshaft.
If you have a vehicle with no air intake/exhaust, you may not feel the effect. Rather, Normal cam is better if the air intake and exhaust are NORMAL. even Normal cam is not to be underestimated. The →ST-1M has characteristics similar to NORMAL. Normally, changing the high camshaft will make it harder to drive, but this ST-1M is a fee ring that retains the NORMAL characteristics in a good sense.

This is a RECOMMENDATION to those seeking a NORMAL fee ring+α.

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