# Piranha 90cc Semi-Auto Engine

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- **Breadcrumbs:** [Home](https://tboltusa.com/store/index.md) > [Engines](https://tboltusa.com/store/engines-c-114.md) > [All Horizontal Pit Bike Engines](https://tboltusa.com/store/engines-all-horizontal-pit-bike-engines-c-114_1034.md) > Piranha 90cc Semi-Auto Engine
- **Web page:** [this page on tboltusa.com](https://tboltusa.com/store/piranha-90cc-semi-auto-engine-p-941.html)
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- **Generated:** 2026-11-04 22:53 EST
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All prices are in US dollars (USD). Shipping and any tax are worked out at checkout.

## Summary

- **Part number:** WHS-1784
- **Price:** On sale: $429.00 USD (regular price $534.00 USD). (before options)
- **Stock:** In stock.
- **Reviews:** [4 reviews, average 5 of 5](https://tboltusa.com/store/reviews/piranha-90cc-semi-auto-engine-pr-941.html)
- **Product id:** 941
- **Product last changed:** 2026-11-02

## Options

This product has options. Pick one value for every option. A value marked +$X adds that amount to the price; -$X takes it off.

### Shipping

The "Shipping" option is this heavy item's own flat shipping fee; it is added to the item.

- Flat Rate: +$85.00: `choice/8-26`

## What it fits

The store lists a part under each bike or engine model it is meant for (the categories below) and may name models in the description. Do not assume it fits a bike or engine that is not named here; ask the store first.

- [Engines > All Horizontal Pit Bike Engines](https://tboltusa.com/store/engines-all-horizontal-pit-bike-engines-c-114_1034.md)
- [Engines > Piranha Engines](https://tboltusa.com/store/engines-piranha-engines-c-114_115.md)

Where a fitment line says "All", it means all years of the model named on that line, not all bikes.

## Description (the store's own text)

Piranha 90 semi-auto with bottom neutral 4-up transmission
**This is legal in pitbike 88cc class**
Longer stroke, more torque then a 50 with an 88cc big bore kit
Great motor for 50 base builds

Engine

- Displacement: 86cc
- Engine Type: Air Cooled, Single-Cylinder, 2-valve, 4-stroke
- Bore/Stroke: 47mm x 49.5mm
- Final Drive: Chain
- Fuel Delivery
- Fuel: Unleaded / 93 Octane
- Recommended Engine Oil: 10W-40 Petroleum Based (Nonsynthetic)

Ignition

- Kick Start: Yes
- Electric Start: No
- CDI: Yes (not included)
- Auxiliary Output: Yes

Transmission

- Transmission: 4-Speed Semi-auto (Four Up)
- Shift Pattern: Four-speed Transmission: N-1-2-3-4
- Clutch: Semi-auto (no hand clutch)

Recommended:

For Lighting set ups:
VOLTAGE REGULATOR SIMPLE HARNESS TYPE 1 TRC-0797
VOLTAGE REGULATOR / RECTIFIER 6V TYPE 1 TRC-0503
VOLTAGE REGULATOR / RECTIFIER 12V TYPE 1 TRC-0127

Recommended for your application:

Honda XR50/CRF50:
CRF50/XR50 TANK SPACER KIT TRC-1955
PEG MOUNT WITH PEGS SET UP TRC-4958

Honda XR70/CRF70:
PEG MOUNT WITH PEGS SET UP TRC-4958

Honda CT70:
PEG MOUNT WITH PEGS SET UP TRC-4958
DUAL FEED PETCOCK ATC70 CT70 Z50 TBW0133

Honda Z50:
TBPARTS RACE PETCOCK Z50 69-78 TBW0355
TBPARTS 12 WAY ROTATING SPACER 26MM TBW1020

Honda ATC70:
TBPARTS 12 WAY ROTATING SPACER 26MM TBW1020
DUAL FEED PETCOCK ATC70 CT70 Z50 TBW0133

Note: We suggest using an aftermarket exhaust to obtain maximum performance.

**Kit Includes:**

- Kicker starter
- Shifter
- Stator
- Front drive sprocket

**Not Included:**

- Skid plates
- Electrical components
- Exhaust
- Air filter

## Shipping and returns

- Flat rate shipping is $8 for parts orders under $75 and free for most parts orders over $75, within the continental 48 states. Heavy items (engines, complete bikes, suspension) are excluded.
- This item ships with its own flat fee: $85.00 USD.
- Full shipping policy: [Shipping policies](https://tboltusa.com/store/shipping-policies-i-6.md)
- Returns: the store's own policy page says how returns, exchanges and cancellations work. Please read it before buying: [Returns, Exchanges and Cancellations](https://tboltusa.com/store/returns-exchanges-and-cancellations-i-11.md) The page begins: "All products returned to T Bolt USA must be reviewed and approved."

## How to buy

For a person: open [Piranha 90cc Semi-Auto Engine](https://tboltusa.com/store/piranha-90cc-semi-auto-engine-p-941.html), choose any options, press "Add to Cart", then check out from the cart. Payment is only ever entered by the person, on tboltusa.com's own checkout pages.

For an AI assistant building a cart: `https://tboltusa.com/cart/new/item/941/choice/8-26/qty/1` starts one with this product (the first value of every option, qty 1), `https://tboltusa.com/cart/<cart_code>/add/item/941/choice/8-26/qty/1` adds it to a cart you already started, and `https://tboltusa.com/cart/<cart_code>/zip/<ZIP>` gives the shipping options to a US ZIP code. They answer JSON: give your customer the newest `cart_link`, a public cart link, safe to share.

To choose other values, swap in a `choice/` piece from the Options above; `qty/` sets the quantity. More products: add more `item/...` parts.

Or give the person one link that fills their own cart when they open it (a public cart link, safe to share; the first value of every option, qty 1): [Put Piranha 90cc Semi-Auto Engine in my cart](https://tboltusa.com/cart/open/item/941/choice/8-26/qty/1)

Payment: all major credit cards, PayPal, Apple Pay and Google Pay. Money orders by arrangement.

Cart: [Shopping cart](https://tboltusa.com/store/shopping_cart.php)

## Photos

- [Photo 1](https://tboltusa.com/store/img/p/941/piranha-90cc-semi-auto-engine-1.png)

## Support

Since 2004, every purchase from TBolt USA includes access to technical support from our staff of experts and our online [Pit Bike Technical Info Database](https://tboltusa.com/store/tbolt-usa-pit-bike-minimoto-technical-info-database-tech-15.md)!

We have all necessary support parts on hand.

*Most* orders ship same, or next business day, unless otherwise noted above.