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TB Parts

TB Race Head, 88cc Bore & 20mm Carb Kit - Z50 K1-81 Models TBW0952

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  • $ 358.95

In Stock

We've stood behind these products 100% since we opened in 2005. Best reviews received for a big bore kit hands down!

Race Head, 88cc Big Bore kit, and 20mm Carburetor Performance Kit:
Z50 K1-81 Models

This Race Head has been updated for even more performance!  It now has 25/22mm valves with better porting/flow.  We also kept the combustion chamber the same size and changed the angle of the valves slightly. This will really wake up your stock engine and is comparable in power to the much larger Chinese 124cc engines!!!

Includes the following:
NEW! - Main jet kit is now included for FREE! 
Lightweight aluminum cylinder with steel sleeve
- Cast in mounts on cylinder for aftermarket skid plates
- Oversized cooling fins on cylinder for efficient heat dissipation
- 52mm high compression piston with rings, pin, & clips
- Head gasket kit
- High performance race camshaft and Honda cam sprocket
- Race Head – Larger valves (now 25/22mm) and better flow for increased performance. Also has bigger cooling fins. Includes all necessary parts and comes assembled!
- The exhaust valve has been upgraded to stainless steel (21-4N material).
- 20mm Performance carb assembly. Includes: 20mm carb, intake, heat-stop, gaskets, mounting hardware/wrench, long adjustable throttle cable, and a air filter. (Cable does not work with older slide style throttles. You must use a newer CR style throttle which we sell in our store. Search ebay for item# 291876353333

We recommend purchasing a high volume oil pump kit, and installing it while installing the bore kit (requires cylinder removal).

International Shipping:


We use only USPS Priority and Express Service when shipping parcels to anywhere other than the USA. Items ship within 5 business days after order. International shipments normally go out Tuesday/Friday. To find out more about internation lead times please contact PRIOR to making your purchase.

Allow 4-17 business days for shipments to Alaska, Hawaii and International Orders

We are not responsible for carrier or customs delays.


Import duties, taxes and charges are not included in the item price or shipping charges. These charges are the buyer's responsibility. Please check with your country's customs office to determine what these additional costs will be prior to bidding/buying. These charges are normally collected by the delivering freight (shipping) company or when you pick the item up – do not confuse them for additional shipping charges. We do not mark merchandise values below value or mark items as "gifts" - US and International government regulations prohibit such behavior. Please do not ask us to falsify shipping documents, it is a federal crime. Any item purchased from us is shipped as merchandise with a commercial invoice from eBay. The receiver of the parcel is fully responsible for any duties, taxes, or fees assessed by Customs and/or USPS as a result of importing the parcel into the country. Factory Motorsports Racing will not be responsible for import duties, taxes, or fees on any international shipments.

Refunds will not be given on refused/undeliverable international shipment for any reason. No exceptions!




Item Availability:


Items are listed when current stock is available, but we sell the same products in our store as our online store. If the item won is no longer in stock at our warehouse and is not available from the supplier direct, full refunds will be given. Buyers will be notified within 1-2 days after payment is received if an item is not in stock.

We make every attempt to keep only parts in stock listed but, that is sometimes a very time demanding task to keep updated here on eBay. If you want to check stock prior to bidding or placing an order feel free to message with your request and be sure to include part number and/or listing item# with description.